A noun referring to one who most likely has, will, or is engaging in an activity that is idiotic in nature when compared to everyone else's current activity. Much like how a group of sober people would perceive a drunk person.
"I'm going to throw that fluorescent light bulb"-Alex
"Don't throw it"- everyone else
Alex throws the light bulb and it shatters.
"Don't move police. I'm going to watch you clean that up"-Old Retired Cop
"Way to go rum-dumb"-Josh