One of my standard carry guns is a cut-down S&W model 10. It fits in my right front trouser pocket with little showing.
Of course, I'm 'old' (lower 60s) and don't wear tight clothing anymore. For those who wear trousers so tight a casual observer can count the change in your pocket, this probably won't work.
Another pistol that served well is the Star BKS (I think that's the aluminum frame model) in 9x19 chambering. They are not made any more, but available on the used market. The Star PD in .45 ACP was a pretty decent pocket pistol as well. Neither were intended for constant shooting, but they held up fairly well. Too bad they haven't been adopted by someone else.
I will confess this: For those times I cannot wear a jacket or outer garment, I prefer an appendix carry with a IWB holster and a non-tucked polo or golf shirt. (Second confession, I play neither polo nor golf.)