Dealy-bobber, whozit, thingy over here. And I like dongle, although I’m sure I’ll get in trouble using it 'cause it does sound obscene.
Flux capacitor
Whizpin
Thing- a-ma-doogle.
Doo-hickey.
F’n f’er thing.
Was raised on Long Island and I say “thingy” as well.
But mostly I say “Doodely-doo”. “Um, uh, hand me that doodely doo!” My husband thinks that’s a bit strange, but I like it!
Let’s not forget the legitimate;
Gimcrack, gew-gaw, dingus, dofunny and whatnot.
I use doinker, but only for something that is used on something else. Like all barrettes and hair elastics are called hair doinkers. Or that thing that helps to open jars is the jar doinker.
I also sometimes say hooker dooker. Where I picked that up, I’d love to know.
Otherwise, I say thingie.
I use either thingamajig, or doozy-whatsits. I’m British.
Hey, you know that, that, Oh …wuthtfukizit ? 
Damn, I can’t believe I misspelled **wuthafukizit **
Amongst certain types in the UK there’s a tendency to say ‘ooojumaflip’ but it is a tiny bit forced and pretentious, IMHO.
I just remembered my father’s favorite “hooskidu”. I thought it was great that my dad somehow learned Swedish, like that company that made that game.
Don’t remember the game, all I remember is that my Dad could talk Swedish.
the festeris (fa-steris)
“Susan, where’s that thing…you know, the black thing…oh,you know…the festeris.”
Yim yam is the main one when our family get together.
We are not averse to doo hickies, wotjercallits and wotsanames, but the name for mechanical ones is always giggle pins.
Very articulate, us.
Around our house, all gidgers that go in your hair (pins, clips, bands, etc.) are “Hair dooders.” Everything else is a “phing”–as in where did I put that, uh, writer-phing?
thingamajig
whoosiewhatsit
thingamabob
whatchamajigit
whatchamacallit
I’m giggling just typing these words. I’m such a maroon.
Am I the only “whosamacallit” person here?
I go for the seldom used “thinger.” I find it to be much more tastefull than the vulgar “thingy.” I also use “shwack(er)” (not to be confused with “shwag”)and “shwooper.” Any of these words can have a long “e” or an “er” added to the ends. For example:
Take the thinger and tie the shwag back to the shwacker to avoid tangling up the shwoopey.
And strangely enough, people seem to understand me.
I’m a Whatchamacallit fan, but I find that my family is the only one I’ve met to use a modified form of “thingy,” which is “tsicky.” I don’t know how it would be spelled for real, but since it’s not a real word, I guess it doesn’t matter much. It does have a slight “T” sound right before the “sicky” part, kind of like in “tsunami.”
It depends on the thing in question. Obviously, any small electronic or mechanical device is a “gizmo”, and an animal or insect is a “critter”. A person could be a “whozits” or a “whatchamacall’im/'er”. Anything else is a “humminawhatzits”. (Pardon me if any of those are misspelled, but my dictionary wasn’t very helpful.)
I should also add that I once used “thingymacdoodley” in a moment of utter frustration, but I felt completely mortified immediately after it flew out of my mouth. Never again.
I’m Californian, born and bred, if that makes any difference.
I call 'em “Dealys” thanks to Homer Simpson.
And I use “Whodidwhatwherewithwhonow?” when I can’t understand what someone said.