When you are having sex and you put your cock and balls completely inside the girls vagina like a poncho protecting you from the rain.
Me:"Last night I was fucking this girl and I tried to give her the Poncho!"
You:"What the fuck is a Poncho?!"
Me:"You know! When you put your cock n' balls all up in her junk ."
You:"Ohhh, gotcha... you're fucking sick..."