noun. Caution: May not refer to a mother-help-across-the-street-er.
Real citation: "i had a small one done to me, but it was good though. me and one of the tech's are always at war with each other. he didnt waste anytime. he comes into work at 8, and immediately comes up to me and says did frank talk to you yet(my boss, and i was off yesterday). so i said no what goin on. he tells me that they're gonna transfer me to another store, one that sees noooooooooooo kind of business what so ever. im flat rate so thats a nightmare. so im walking around the next half hour just saying stuff like expletive this and expletive that, im gonna quit. he lets me mope for about a half hour and with a smirk asks me what day is it. i say its april 1st, its april foo.......you motherexpletiver! you couldn't even say good morning first."
(April 2, 2008, TunerFriends, http://www.tunerfriends.com/forums/archive/index.php/t-12138.html)
Made-up citation: "I am a bad motherexpletiver. Not everyone knows that. Under this professorial cardigan beats the heart of a Viking crossed with a wombat hopped up on steroids and pixie sticks, with tremendous street cred."