A sexual act in which a male mastrubates into a bowl of rice pudding, and then gets sexually aroused as he watches the unknowing individual consume the pudding. This was a popular practice among college students in the 1980's and is still widely done in southerb europe.
"Dude check out tina! She is totally shoveling down that dirty rice pudding that's sick!"
Dirty Rice is a term that basically means "a shit-stained pussy". It occurs mid-coitus when you pull out of the anus and proceed to insert into the vagina and continue coitus.
Your friend awakes from a daydream to declare "last nite I was banging your mom in the butt then I pulled out and put it in her vag!!" Which is then followed by an observer declaring, they call that dirtyrice!!