When you're doing a girl doggy style, pull out, and cum on her back/ass. When she tells you to wipe it off, you pretend to, and when she wakes up, she has the bed sheets stuck to her back like supermans cape.
Beating a girl from behindand then busting jizz all over her back... then when she lies down on the sheets the sheets will stick on to her back - superman style
Tyrone: im bout to superman that hoe tonight
Jamal: nigga, you done gone ruined your sheets then
Tyrone: its worth it when i see her get up with a sheet cape on her back.
Its when you don't have the time or effort to go through with a complete supermanning of that hoe. So you put a post it with a little superman symbol on it, so it looks like a mini cape.