1. The act of one's stink in a public bathroom being overridden by the next guy to take a dump.
2. To have another's dump cover the fact that you stunk up the restroom.
3. When someone comes into the restroom to take a shit just as you're wiping.
Broski: Dude, I had Chile con Carne last night and completely blew up the mens room next to the boss' office just now.
Dudemeister: I can never dump at work. I'm too worried everyone will know how foul my shits are.
Broski: Yeah I normally have the same problem but as I was finishing up, Jeff went into the stall next to me.
Dudemeister: That's lucky. Jeff's fat dump is going to totally poopersede your foulness.
Broski: Yeah, and I've been nailing his wife!