I once took a meeting with a new client, spent two hours in a room with him and his business partner hashing out the terms of their acquisition of a company then left the office and went to pick up my kid from daycare. Took me maybe 10 minutes from end of meeting to arriving at daycare. New client's kid goes to same daycare facility, I see him there, start talking to him and the whole time I'm wracking my brain trying to figure out who this guy is, keeping the conversation as general as possible so as not to let on that I don't know. Ultimately it was the nametag on his kid's backpack that tipped me off.