A belt would hold up your pants much better than your method. Walking down the street, clutching your manhood through your jeans just isn't very attractive.
Dude. That looked uncomfortable. How long did you walk like that? Are you trying to impress the lady-friend (who was no fashion plate herself) walking with you? Did someone tell you that if you ever took your hand off your member that someone would steal it? If so, you need to get over that.