OK, probably TMI, but here's what works for me.
I usually just tuck lightly in briefs with a modest amount of compression, such as Flexees. When I'm wearing a skirt, A-line, or tights, I'll go to a more industrial-strength tuck using 2" micropore medical paper tape, looped across the member, crossed behind, and pulled back in the gluteal fold. This lets me void while sitting, but keeps 'the bump' from showing. (Make darn sure you don't catch any hairs on the tape. I keep things landscaped...)
