I agree with other responders; this is exactly how weak players play a J. I guess he didn't have one given the tone of your post, but still risky.

That said, this play is a very big part of my game against weak players. It works much better when they make it clear that they don't have the trips i.e. betting out quickly into a paired flop with no draws possible. Against weak players this is almost 100% a pure bluff or two pair, and most weak players have learned that a call on the flop followed by a raise on the turn here means trips, and they tend to think for a while and proudly fold.