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
Get the The Gru Cardmug. A close synonym to gross (as in sick). Something is considered "grus" when you have the urge to want it in your possession or consume it. Often referred to food or clothing.
by chocolate1234567654321 February 24, 2022
Get the Grusmug. 
by Dinkies Stinky Shart July 21, 2022
Get the Grippy Grumug. .
by LeSouffleDeVersailles February 15, 2025
Get the 《¤》Gyyh《¤》Gray 《¤》 Grey《¤》《¤》gyyh《¤》 Gri《¤》Gru《¤》Groj《¤》Gyyh《¤》mug. A Tall Man from Despectable Me
by ISTHISAMOGUSAMOGUS February 2, 2024
Get the Felonious Grumug. 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
Get the gru is risingmug.