If you click multiple times to respawn, you can press switches with your butt as soon as you spawn. In Deathmatch, if a start is placed in front of an exit - even with your butt facing it - can cause some real BS deaths. (My apologies if this has already been reported, may be related to the 'Respawn Desync' bug??)

Here's a demo, requires tdevil2.wad - http://www.mediafire.com/download/o5inuj5v7cjlc79/ass_switch_glitch.odd

At about 2 minutes in, you can see I spawn facing away from a blue door, yet it says 'you need a blue key to open this door', showcasing the "pressing stuff with your ass" glitch as I like to call it.