Green’s Dictionary of Slang

shrimping n.

toe-sucking.

1999		Gaymart.com Queer Sl. in the Gay 90s 🌐 Shrimping – Toe-sucking.
2013		J. Stahl Happy Mutant Baby Pills 232: I told them about shrimping [...] the first time I had heard about toe-sucking it was under Clinton.