This is a meme-type joke, and the creator of this post is not sure if it is real, and physical, but in the meme world, it is one of the recent memes. It has many variations, ranging from making people infinitely gay, to making Pokemon bored. The character that is both a picture on most of these "Cards" and the namesake would be Gru, a character from the movie Despicable Me. Now, onto what the card actually does. The most common thing it does is reflect all No u's and make all players gay. As I have said before, there are multiple variations of it, but I cannot name them all.
Dude 1: Ur mom is gay
Dude 2: No u.
Dude 1: No u.
Dude 2: No u.
Dude 1: NO U!
Dude 2: I play the Gru card!
Dude 1:Noooo!
Dude 3: What are you guys doing?
Dude 2: *Whispers*
Dude 3: WHY AM I GAY?!
Dude 1 and 2 together: That's how it works.
Dude 2: No u.
Dude 1: No u.
Dude 2: No u.
Dude 1: NO U!
Dude 2: I play the Gru card!
Dude 1:Noooo!
Dude 3: What are you guys doing?
Dude 2: *Whispers*
Dude 3: WHY AM I GAY?!
Dude 1 and 2 together: That's how it works.
by ISoundTooSophisticatedButImNot February 20, 2019

by Dinkies Stinky Shart July 21, 2022

A Tall Man from Despectable Me
by ISTHISAMOGUSAMOGUS February 2, 2024

It is a sentence uttered by Kevin the minion during the climax in minions the rise of gru explaining gru the main character rising into the heavens after licking bull nipples but now it is commonplace to use the phrase as a feeling of extreme happiness and excitement
by Ottoman Empire enjoyer August 2, 2022

A Sex Position In Which One Uses Their Noses On One’s Privates Then Smell Them! The Couple Will Win A Ticket Of 2 To Minions: The Rise Of Gru If They Can Recreate A Random PornHub Scene Of Choice
Afaan: Ani Luna Irratti Gru Fuck Maneuver Raawwadheen Tikeetii 2 Gara Rise Of Gru Cause Isheen Stepbro Irra Deebitee Uumte Mo'ate!
Tom: So You Performed The Gru Fuck Maneuver And Won 2 Tickets To Rise Of Gru Cause She Recreated Stepbro!
Affan: Eeyyee!
Tom: OK!
Tom: So You Performed The Gru Fuck Maneuver And Won 2 Tickets To Rise Of Gru Cause She Recreated Stepbro!
Affan: Eeyyee!
Tom: OK!
by TMIpixel July 2, 2022

Forcefully shoving gru's fat long shnooss in a minions fat juicy butthole. Then taking his hands and ripping the minion into 2 pieces and putting both into his nose holes.
by PossibleHeadass July 11, 2022
