I have the Crazy Cat Lady action figure.
We have a pair of cuddly frogs wearing elephant masks sitting on top of a set of shelves…
And I bought a tetris light, like ZipperJJ did and yes, it’s pretty useless as a light - but very neat!
A can of Double Yellow Brand Sun Dried Possum. (yes, without the O) It has a prominent place in the kitchen and never fails to elicit comments.
A “Mooning Santa”. My niece and nephew think it’s the greatest thing they’ve ever seen.
I would like to add, since we are Pagans and fans of fantasy art, there are many, many, many other things, too. It freaks out the newbies from the housekeeping service. Doesn’t matter what it is, a dragon, a green man, a Pan figurine, they are all ‘diablos’.
One year for Halloween I wanted to be an android with a turtle at the controls. I bought a cheap plastic torso, the kind made for clothing displays. I cut it in half so I could wear the front portion. And in the stomach area I cut a sideways H shape so it could open up like doors, behind which I attached a small compartment into which I could fit my turtle. Anyway, this torso is hanging on my wall, and inside the doors I’ll display different things depending on my mood, like a turtle plushie, or a plant. Another year I was a fallen angel and I had black wings that I then suspended in front of the bay window until it got too dusty.
I have a ton of posters and knick knacks and toys and statues and things all over the place but that’s probably the most interesting.
I always wanted to get the “B movie people running in terror” figures from the same series, and place them in front of my friend’s cat for a photo op.
A six inch tall silver figure of Sideshow Bob that separates at the waist, revealing a one inch serated knife attached to the top.
I have a clockwork Gort, who walks and whose visor can be opened (disintegration beam sold separately), lava lamp, and a ceramic Dilbert. My son has a Portal gun (small size) which works as a night light.
Robots. I have lots of robots. Wall-e, R2-D2 (a couple of variants, including a trash can that I converted into an R2-D2-ish robot, and a plushie R2-D2 as well), some smaller robots, and a small army of wind-up robots of several different types. I also have a few other wind-up toys like a chicken, a rabbit, a butterfly, and a fish.
Aside from R2-D2 I have a bunch of other Star Wars novelty stuff. I have Luke and C3P0 land-speeder bobbleheads, a plushie Darth Vader, and a Darth Vader alarm clock (not sure if that actually counts per the OP since it does serve a purpose as a clock).
I have a plastic Snoopy on a base that plays the peanuts theme if you push the button (or it would if the battery wasn’t dead). I have a small sailing ship. I have a couple of wooden antique-style cars.
I have a lot of brain teaser type wooden puzzles. I have a couple of Rubic’s cubes.
I have an antique car pencil sharpener and three antique car matchbox cars.
And I have a flintlock style toy cap pistol.
The mantelpiece above the fireplace in my red and black kitchen is topped by a complete set of White Stripes Russian Dolls.
The SO would say everything in my home is a novelty item! She’s made me put such things away. (She’s been known to hide my gargoyles when guests are coming over, so as not to make them think we’re weird. I like weird, and I remind her that I’m ridiculous.)
The first thing that came to mind though, when I read the thread title, is my A-7E ejection seat (example photo). I had it in my living room in L.A., but it’s stored right now. I don’t think it will fit in with the SO’s decorating plans.
I have this rather large Little Nipper.
Shhhhhh! I got one for the SO’s birthday present (in November). She guessed what’s in the box (bad luck she was here when it arrived!), but I neither confirmed nor denied it. She’d mentioned that she’d always wanted one, though she admitted she has no use for it.
We have a fair number of odd bits floating around, but I have an especial favorite: When he was eight or nine, The Boy’s art class assignment was to make a holiday themed decoration. A couple of kids made dreidels, some made snowmen, or angels, and there were several popsicle stick reindeer ornaments, yarn stars, and glitter infested snowflakes. I was thrilled to receive my crude-but-recognizable articulated Chthulu holiday puppet. He remains on display.
Most my novelty items aren’t on display at the moment, I have plenty of odd things I’ve collected over the years.
Right now I have a super large mug from starbucks that says ‘boston’ on it. It’s about a foot tall and proportional to your standard mug. My uncle gave it to me when I first moved out of MA. For whatever reason people like it a lot.
I have a few chain maile shirts around I made a number of years ago. One steel and one black anodized aluminum.
I have a bunch of random star wars toys and things but I kinda outgrew them so they aren’t out anymore.
Some day I’ll actually set up my living room again but I never used it in my last place so everything is boxed up sitting there ready for me to unpack it and not use it here. It’s been a few years.
Andreas Baader coffee mug, if you need that killer boost in the morning.
Lizzie Borden bobblehead.
Mummified frog
Walking around my house, I can spot several novelty items, including but not limited to:
A barefoot battery-operated Santa Claus that played a MIDI version of “Winter wonderland” while saying “Ow, my feet,” over and over again. He had a little wooden chair that broke long ago. This is part of my late mother’s collection of Christmas stuff, which also had a cowboy Santa that played a country version of “Holly Jolly Christmas.”
A 12" porcelain fairy riding a unicorn. It currently resides in my daughter’s room.
A clay hand-painted Superman, made by my ex when he was in elementary school. It sits in my daughter’s room next to the fairy and unicorn.
My collection of Starbucks ceramic cups from various U.S. cities and a couple of foreign countries. Right now I have Seattle, Las Vegas (travel mug), Dallas, Fort Worth, Boston, El Salvador, and the latest, China, courtesy of my dad. I will add San Francisco later this year.
My Captain America and Iron Man bobbleheads. Just to bug my daughter, who is not much of a fan of this pairing, I once put a tissue on Iron Man’s head and threatened to take a wedding picture of the bobbleheads. 
It would be awesome if it opened and closed when you said Klaau barada nikto.
Some day I will have the tackiest novelty item ever made; the Christmas Story Leg Lamp.
Let’s see…where to start? My decorating scheme leans pretty heavily on gewgaws, trinkets and vacation tchotchkes. How about a horny toad bowl, or a jackalope piggy bank?
