The Office Season 7 Episode 21 (04/28/11)
It is Michael's last day in the office, only he tells everyone else that it's his second to last day. He goes around to everyone, saying his goodbyes and giving them presents. Jim figures out that it is actually Michael's last day, and helps him realize that it is the correct decision to leave with Holly.
Meanwhile Deangelo and Andy go on a sales call. Deangelo gets psyched up by visiting an animal shelter, and then completely blows the sale. Andy picks up the pieces after Deangelo leaves the office of the client, and ends up making the sale.