Up to something big

"Gee Brain, what do you want to do tonight?"
"Same thing we do every night Pinky, try to take over the world."

They're both plotting to sh*t there pants on the spot.

Looks like a new meme

The baby on the left looks like the meme "oh stop it you" dog

"So, Ferb... what do you want to do today? "

I solemnly swear that I am up to no good :D

Probably butt sex