Oh My Cthulhu - a replacement for "Oh My God" (aka "omg") for those who prefer one (for whatever reason, including you're not religious or you're too religious to feel comfy using "god"). OMC evokes the great chaotic deity from Lovecraftian lore. Often used humorously.

Additional exclamation replacements include:
"Cthulhu's spawn!" instead of: "Jesus Christ!"
"Praise the Chaotic One" instead of: "Praise the Lord"
anyway you'd use omg
"OMC, what was that sound?"
by CuteyPatootey April 03, 2015
Get a OMC mug for your buddy Paul.
Basically a replacement for OMG, but instead of god at the end I thought a more iconic figure:Charizard.
The meaning is can range from surprise to 'that's just awesome'.
Everybody I just won the lottery, OMC!
OMC, that guy just jumped off a bridge!
by HippoPenguin October 03, 2010
Get a OMC mug for your dad Vivek.
O.M.C=Over mature child
Used to poke fun at someone who has a mature face but likes things normally associated with children or acts childishly.
Ben: Glenn, stop being so lame and childish, stop telling me about your adventures about you and your power ranger figurines, for god's sake, you are already 21.

Glenn: Mind your own business.

Ben:Whatever, how OMC can you get?
by Spentaz September 04, 2009
Get a OMC mug for your fish Callisto.
Acronym of Oh My Chad, a variation of oh my god, originating in the Disney channel series Sonny With a Chance. Commonly used by screaming fangirls.
Person 1: Do you like the movie Starstruck?

Person 2: OMC, it's amazing!
by thequeenofallruralsuburbia August 10, 2010
Get a OMC mug for your Aunt Beatrix.
To hang out with friends for a short period of time, usually for 45 - 90 minutes.
It is looked at as a bad thing to do, not very proper.
"yo can you chill today"
"I dunno, if anything it will be an OMC"
by Schnitzeled May 20, 2009
Get a OMC mug for your Uncle Günter.
OH MY CUTENESS!
its like OMG but for cuties... or non-religious people..
Did you check out that boy? it was like totally OMC!
by emmzz September 05, 2010
Get a OMC mug for your dog Rihanna.