Missing In Action, meanining when people are at a social gathering and one person that usually hangs with this crowd is not there either because he wasnt answering his phone or he has found a cooler crowd to hang with.
"dude where is johnny? i havent seen him in like a week."
"Yeah man he's M.I.A, no one has seen him in a while, he is never answering his phone and brenda said she saw him hanging out with these other people"
"thats so weird"