Sometimes I get a boner at work, but thats usually not much of a problem as I'm behind a desk for 90% of the day. However, at times, several of us go out in a car, I get bored, start thinking of stuff, and end up with my cock stretching down my leg. The only thing I can do is put my arm across it hoping no one else notices and it'll go away. I can usually feel what feels like my pulse through my jeans though, which usually just makes it even harder for a small while.
I've only ever had to visit the nearest rest room once for a jack off session though, and that lasted less than a minute and took ages to clear up afterwards as I wasn't ready for it! | 
