The Case of the Missing Scrub Pants

I did the laundry today and pointed out to Brian that his baby blue scrub pants were missing.  "Oh, so that's where they went," he immediately replied.  The pants that he's been seeing for the past 4 days, right next to his usual seat in one of his classes turned out to be his own. hahahaha.  With a confused face he says, "I thought to myself, same color and same size, but I didn't think it was mine." How in the world did he lose his pants and later not notice them right in front of his face? hahahha.