A hip hop dance move. Poppin your back while you drop it like it's hot. The most basic way to describe it would be repeatedly arching your back so that boobs and bottom pop out while slowly bending at the knees until you almost reach the floor.
the act of becoming bored and/or aroused while taking a dump, and subsequently masturbating. alternatively, "drop and pop," depending on which comes first.
"dude, you were dropping a deuce for like 25 minutes. did you get lost?"
"no, man. i thought about your momin there, had to have myself a pop and drop."
Chorus: Toot that thang up mami, make it roll. Would you Pop Lock drop it for me girl, get low. If your mama gave it to ya baby girl, let it. show. If you pop lock drop it for me maybe we could roll. OHHH! Pop Lock and Drop it x7