Sigh this is showing my age, but:
My brother thinks I’m some sort of savant because I can sing, word for word, the themes to The Banana Splits, The Flintstones, The Monkees, The Bugs Bunny-Roadrunner Hour, and The Jetsons, and, if called upon, can do Hawaii FIve-O, complete with horn and flute riffs. Also the Good & Plenty commercial with Choo-Choo Charlie and the dialog from the “Hey, Mikey!” Life Cereal commercial.
Anybody else have this crucial and outstanding talent? 
Heck yes; doesn’t everyone (those of us of a certain age that is)?
It’s kind of the same with my brother and me. He’ll usually remember the words if I bring up the song but if I didn’t bust out the Jack in the Box jingle (Jajajack Jajajack Jajajack Jack in the box, now you’re cookin’) it would all be lost in the sands of time.
I feel a game thread coming on; finish this lyric:
“Here we come on the run . . .”
“Have Gun Will Travel reads the card of a man…”
“Who is the tall dark stranger there? Maverick is his name…”
“Here’s Cathy who’s lived most everywhere, from Zanzibar to Berkeley Square…”
(Christ, I’m old… 
)
“We are the Freakies, we are The Freakies, we live in the Freakie tree. We never miss a meal, cause we love our cereal…”
George, George, George of the Jungle, strong as he can be
George, George, George of the Jungle, watch out for that treeeeee…
In Heaven Sent, suddenly, you are all the things you want to be, a little bit naughty but heavenly…in Heaven Sent!
He’ll fight for freedom where ever there’s trouble. GI Joe is there.
I’m 54, went to Expo '67 in Montreal, and can still remember the promotional theme song:
“Hey, friend! Say, friend!
Come on over!
Looking for happiness?
This is the plaaaace!”
Oh, and the theme for the long-lost Palisades Amusement Park:
"Palisades amusement park,
Swings all day and after dark!
Ride the coaster!
Get cool
In the waves
Of the pool.
You’ll have fun!
SO, come on overrrrrr."
Ohhhhh, do I have this talent. As a former boss of mine used to say, “Mind full of garbage.”
I could fill the page with a list of the TV themes and jingles I can sing from memory. But instead I’ll just challenge you with some of the more obscure ones I know:
Nanny and the Professor
Eighth Man
Mighty Hercules
The Smothers Brothers Show (the sitcom, not to be confused with The Smothers Brothers Comedy Hour)
It’s About Time
Captain Nice
I Married Joan
My Mother the Car
…and the real stumper…
The Ugliest Girl in Town
Holy cow, you stumped me with *all *of them, except
“Phoebe Figalilly is a silly name
And so many silly things keep happening
What is this magic thing about nanny
Is it love or is it magic?”
God I miss show themes and product jingles:(
I’m guessing we’re about the same age!
“There’s a prehistoric monster
Who came from outer space,
Created by the Martians
To destroy the human race…”
“It’s about time, it’s about space,
About to land in the strangest place…”
"The end of the Civil War was near,
When quite accidentally,
A hero who sneezed abruptly seized
Retreat and reversed it to victory.
His Medal of Honor pleased and thrilled
His proud little family group.
While pinning it on, some blood was spilled,
And so it was planned he’d command…
F Troop!"
Don’t go to bed with no price on your head.
No! (Don’t do it!)
Don’t do the crime if you can’t do the time.
No! (Don’t do it!)
And keep your eyyyyyye on the sparrow
When the goooooooing gets narrow.
YA!
Where can you go where the cold winds don’t go?
To the tune of "Yankee Doodle"
“So, come and join us, all you kids,
For lots of fun and laughter,
As Roger Ramjet and his friends
Get all the crooks they’re after…”
"Stand a little straighter,
Walk a little prouder.
Be an innovator,
Laugh a little louder.
Grow forever greater,
We can show you how to.
Where will you be then?
March along, march along, march along to the song of the Merry Marvel Marching Society!"
Which reminds me…
"Stronger than a whale, he can swim anywhere.
He can breathe underwater and go flying through the air…’
And that’s the name of that tune 
Who isn’t able to sing the theme to Gilligan’s Island?
Secret Agent Man
Green Acres
Beverly Hillbillies
Monkeys (just heard it on KFOG 10 at 10 last week!)
I could go on…
“Have Gun, Will Travel” reads the card of a man.
A knight without armor in a savage land.
His fast gun for hire heeds the calling wind.
A soldier of fortune is the man called Paladin.
Paladin, Paladin,
Where do you roam?
Paladin, Paladin,
Far, far from home.
Hey, hey we’re The Monkees!
Note the spelling.
Come and listen to a story about a man named Jed
Poor mountaineer barely kept his family fed.
Then one day he was shootin’ for some food
and up from the ground came bubblin’ crude
(Oil that is, black gold, Texas tea)
Born on a mountain top in Tennessee,
Greenest state in the Land of the Free
Raised in the woods, so he knew every tree
Killled him a b’ar when he was only 3.
Davy, Davy Crockett!
King of the Wild Frontier.