A rather unfortunately common misspelling of the phrase, "open mic" which is an event staged by bars & nightclubs allow ordinary people to go onstage and sing, tell dirty jokes, or spout off a bountifully overflowing cornucopia of toilet tongue just to try and liven up an otherwise dull house.

Seen in printed material only (such as a sign in a window); as "open mike" and, "open mic" are pronounced exactly the same.
MAY 31 OPEN MIKE FROM 7 TO 11
by Telephony May 14, 2015
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When you are hangin' with your friends drinkin' Mike's Hard Lemonade.
"Hey, I brought the booze! It's Open Mike Night!"
by bhp May 28, 2013
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