It means in Swedish "Runkar Snoppen" or when translated to english "Jerking Off", which is not really a direct or perfect translation but you get the point right?

lil mad is like big mad but the opposite, you mad but not mad to the extent of pullin somthin

A combination of english words that are very funny in swedish. It translates to jerking off your penis. It's a wordcombination that kids in Sweden learn in elementary school, and it's used to jockeboi prank your friends.