A while back i was getting the dirty linen out of one of the rooms at my morning job when i noticed a timer sitting on the vanity next to the sink. I did not see anything around or near it that would give a reason for its use so i used my imagination and came of with this idea:

Women need time to put on their makeup and stuff because they believe 'Beauty takes time.'
Men would say, 'BS, you have 10 minutes to get ready. If you aren't ready by the time the timer goes off i'm leaving your a** here.'