The act of inserting your short shriveled chode (short,fat, Pee-Pee) in between two molding hogie rolls or loose roast beef curtain lips preferably from your grandmother or a loud mouthed rent-a-cop who has a hairy brillo pad muff that is often licked by a member of valet services.
\\\\\\\"Hey Conor, You wanna come over here and stick your millimeter peter in-between my saggy tarp lips and we can make the best cocksandwich you have ever encountered\\\\\\\". HOLD THE MAYO!
The act of placing a cock in between two slices of bread (whole wheat or potato, your choice) with any condiments (usually preferred mayonase or mustard) slathering them gently together to create a sandwich of cock, thus cocksandwich, after creating said cocksandwich, violently shove into the partners mouth while defacating on their chest and reaching a climax.
Dude I totally cocksandwiched sally she cried all the way home... I laughed.