Double Fudge Sundae 

When a girl straddles a man on the toilet for sex, but, both people are shitting simultaneously. Laxatives can be taken to enhance the pleasure.

I keep walking in on Jacob shitting in the hopes that he'll ask me to do the "Double Fudge Sundae".

Double Fudge Sundae by StanTheBanana February 3, 2021

Double Fudge Sundae 

When a man is having sexual relations with a womans un-douched anus, and gets his penis covered in fecal matter, and in anger at realizing this, puts his penis in the womans mouth

Hey Andrew, I heard you and your girlfriend broke up after you gave her a Double fudge Sundae.

Double Fudge Sundae by Der Axel March 22, 2009