Cats in the bathtub 

When you are trying to stuff your nuts into a woman's fart pipe and as soon as you cram one in, the other nut pops out. Leaving you with only one nut in her asshole, but never two. - Very similar to trying to get two or more cats in a bathtub, one always escapes when trying to get the other in.

The only man to accomplish this feat is the very famous "aww nigga, nuts in the ass dick in da pussy" porn actor. Who overachieved the feat by keeping both nuts in a females asshole WHILE stuffing his giant dong in her vagina. Making us all feel inferior.

Man, I was trying to stuff my nutsack into Bertha's asshole, but all I got was cats in the bathtub

Cats in the bathtub by TittyfaceJenkins July 5, 2016

Two Cats in the Bath Tub 

The art of inserting one's testicles deftly into a slut's vagina. Then anal penetration via phallus follows.
This is said to be as difficult as giving to cats a bath.

Aidan, after months of practice, successfully got two cats in the bath tub with the woman of Tim's dreams.

Two Cats in the Bath Tub by the d00d October 20, 2006