Replying to How long does it take for eyebrows to grow back?

I already tried a couple places online but found hugely varying answers...

anyway, one of our buddies decided he's going to join the marines. last night on the way to a party our other buddy told him that they give hair tests to look for drugs and he freaked out cause he had only been planning for a piss test. i told him he should check up on that but long story short when we got back to our buddy's later all fucked up, he had us shave his entire body. we started on his legs, then did his head, then one of his armpits, then his chest, and then he asked someone to do his eyebrows. we obviously obliged his requests because we were retarded and it was hilarious. anyway we got too loud and got told to wrap it up by neighbors, so we had to call it quits when he was completely hair free except for his knees, one armpit, and his balls/grundle/ass, which he said he would do this morning

anyway, he's fucked because even if they do give every person a hair test, AND he gets every bit of hair gone (very doubtful), AND that worked, he still has no eyebrows or anything. so how long until his eyebrows grow in?