Its when you have no condom and have to resort to using a plastic bag to have "protected" sex
" yo dude last night at the party me and this chick were real horny and she wanted to fuck but i didnt have a condom so i had to "cram bag" that bitch"
by Pafrick and Renegade March 19, 2010
When you fill a plastic bag so much that you can't tie it closed. You pull a second bag down over the top to seal it closed. This is the cram bag.
I stuffed so much in, I had to use a cram bag
by S0d0r May 13, 2016