When a man or woman gives a man a blowjob while he is taking a shit.
From Harold and Kumar:
Goldstein:Dude, Cindy Kim even gave me a blowken.
Kumar:What's a blowken?
Goldstein:When a girl gives you a head while your taking a shit.
When a girl gives you head when you are sitting on the toilet taking a shit.
Ohh my god i was taking this huge shit last night then some drunk chick came in and gave me head. It was the best blowken of my life.