When 2 girls fuck eachother using their vaginas as dicks.
Dick: Did you see that porno on the internet yet? The girls were sissoring!!
Dbag: Aww! I wish I was there!!!!!!
this is a sexual technique in which two girls (usually) stick their legs in between each others legs resembuling two sissors.
"I was totally sissoring my girlfriend last night it was soo hot."