underduck 

On a swing set, where the person goes under the swing and then lifts the swing, typically what moms, dads and babysitters do to toddlers. But i've seen teenagers challanging each other by making there friends give them underducks.

i remember 7 years ago, when i was little my mom gave me an underduck, and In the GIF i attached it shows exactly with an underduck looks like

underduck by username420 December 4, 2020

Cuban Underduck 

When you bend your dick down and back, and a girl blows you from behind with her nose on your butt hole.

"I got a dandy Cuban Underduck from the broad I met at the bar last night."

Cuban Underduck by TurdFerguson21 June 3, 2016

Uberduck 

Uberduck is just a website for AI voices of fictional and real people. Sometimes the voices can be messed up and not sound like the character or person you want but it's still good to use

Person1: Hey man have you used uberduck?
Person2: No. What is it?
Person1: It's a website that mimics other people and characters!
Person2: Really! WOW! i'll use it now

Uberduck by LoweredUniform July 31, 2022

Underfucked 

sexually deprived

1. Yo look how hard she's hitting on him... she's definitely underfucked!

2. That guy is completely underfucked. He just desperately asked her out again after she told him to fuck off for the third time...

Underfucked by Stephen and friends June 26, 2010

underfuckingstand 

When you don't understand something and you are super pissed.
When you don't feel like saying "fucking understand"
When fucking understand just doesn't quite display the needed emotion.

"I don't underfuckingstand why your acting like this"

underfuckingstand by Desiree Aho January 9, 2008

underdecking 

conspiring against an authority figure to take synchronized shits underneath said authority figure's deck. Usually performed in groups of two to five people. In extreme cases, shit burritos are fashioned with paper towels and left to be found.

Oh, no. Have you seen the kids? I hope their not underdecking us again!

underdecking by underdecked July 2, 2009

underfuckingstand 

underfuckingstand - Understand, with "Fucking" inserted in the middle, making it an exclamation of frustration or, in some cases, a joking statement.

"What part of this do you not underfuckingstand?!?" or "I dont underfuckingstand!"

underfuckingstand by Steve October 24, 2004