We were in Rome some years ago, seated on a train. I was seated on the aisle and witnessed a guy over my right shoulder, standing in the aisle, working on pickpocketing the guy standing to my right front.
I was waiting for the pickpocket to get a little further along before grabbing his wrist and twisting hard behind him, but he realized I was onto his game and stopped.
I was wearing cargo shorts with the flaps buttoned for exactly this reason. Didn’t care about the (lack of) fashion statement.
Yep, cargo shorts with Velcro snaps and inside the pocket a zipper protecting the pocket even more.