I'd agree with the 10 to 11 PM sentiment just out of common courtesy, after that take it inside...
Not to take away from the original question, but I will...A few years ago I used to have a pretty hot looking boss. Our crew was made up of 15 guys (field techs) and 3 women in the office. Twice a year the boss would invite the crew to a backyard party at her home...
On Monday mornings, somebody would always ask (usually a newbie), "what time did you leave the party ?" The answer would always be, when <insert bosses name here> ended up naked, passed out, face down on the picnic table...
Still cracks me up to this day...But, then again.