Let him lick his ass

When someone is being a little bitch and annoying everybody with their meaningless shananigans, you tell them to go lick their ass, as in go whine and bitch by themselves. Applies to females too. Their counter part would be let her lick her ass

Susan: Ugh, becky's whining about her louis vuitton shoes getting dirty at the party yesterday
Mary: Let her lick her ass, i don't have time for her rich girl problems.

Vicky: Shawn's telling everybody that I told him I liked him
Amanda: Ugh let him lick his ass, I swear his ego is the size of jupiter

Jessie: Bro, drake keeps bugging me about my fake shoes
Nick: Let him lick his ass, we all know his are faker than anybody's here.