It'd be hilarious if you taught her how to code Fortran.

Flicking your cheek just right to make the water drop noise

On a vacation when I was a teenager I taught my younger sibling the "SYN/ACK" game.

They still remember the TCP stack handshake protocol including resets and acks years later.

My niece and nephew loved the “this guy” gag. What’s got two thumbs and thinks you’re the coolest? THIS GUY! and point to yourself with your thumbs.

Teach her to order something off a foreign-language menu, invite the family out to dinner, and see if she can place her order fluently.

Doing the "Five year old white girl shocks waitress by ordering Orange Chicken in perfect Mandarian" bit IRL would be pretty funny and adorable.

I've thought my niece that policemen go "oink oink" and that pigs go "You have the right to remain silent!"

Lockpicking

Using Linux

Media piracy

Feeding the homeless

Wheatpasting / graffiti

Political theory

Shoplifting from corporate chains

First Aid

Legal observation

Black bloc tactics

Guerilla gardening

Spotting plainclothes cops / informants

Dialectical Materialism

The Song That Doesn't End

• Beatboxing. "Boots and cats and boots and cats"-style.
• The pulling your thumb off trick.
• The Macarena.
• "The Game". ("You just lost The Game.")
• Chopsticks on the piano/keyboard/toy xylophone/etc.
• "The Name Game."

A buddy of mine taught his 5 yr old daughter to tell people "One time, at band camp...I stuck a flute in my..." *long pause* "nose".

And he gets joy remembering all of the people go wide-eyed waiting for that next word out of her mouth.

Teach her how she can insert "apparently" into every statement.

"Guess what?"

"What?"

"CHICKEN BUTT!"

I taught my niece to say "I can't work like this!". That was fun!

If she's the right age, Teach her The Game. It's a brain virus game.

Rule number 1 of The Game, you can not think about The Game. When you think about The Game you lose.

Rule number 2, when you think of The Game you have to say that you've lost The Game. Ideally loudly and publicly.

Rule number 3, after losing the game you get 30 minutes grace period to stop thinking about it before The Game starts again.

Rule number 4, once you have learned about the game you may either play the game or cheat.

I taught my kid to say "mom drinks beer for breakfast" as soon as she could talk. Wasn't that popular with the family xD

Arm pit farts

How to tie her shoes the instant/quick way. She'll be the coolest kid to all her peers and even amaze other parents who witness it...

https://youtu.be/Q5qZpQe_4EA?si=6fPhLyHs5BwJoaoA

(I have no affiliation with that channel it was just the first thing that came up when I searched)

End every other sentence with ~ nya ~

The drums.

Or a less chaotic-evil suggestion, that water-drop sound made by flicking your cheek.

I have had pretty good luck with doing

High five Up high Down low Too slow

My nephew would just let me do it forever, always trying to beat me on the too slow bit.

I taught my 18 month year old niece the sound a dinosaur makes. ROOOOOOOAAAR

Give her some unconventional future career ideas. Non-edgy ones, of course. I think it would be pretty funny if after a visit from an uncle your kid was talking about sailing knots or embalming procedures or something.

i decided to let her watch Smackdown with me. we'll see what she picks up as a surprise for mom & dad

Teach her to take a drink and then smack her lips and say, “ahhh”.

Juggling ? beginning with two balls is fairly easy and is a slippery gateway to more balls

Pull my finger.

Assembly

Do something that will confuse her parents a ton. Like tell her that every time she wants something, she has to touch her nose three times then say the thing. Demonstrate it a lot to drill it in.

taps nose three times... COOKIES

That it's pronounced heliclopter and not helicopter.

Poker. And proper bluffing.

We got my niece to speak a little Klingon.

Gang signs.

Dad jokes or anti jokes maybe? Math formulas? A foreign language?

Tell her a fun fact, in your best science teacher tone. It takes one billion microseconds to get to one second. Hopefully she can run with this and ask more questions.