Different types do it differently and they do it at different rates, I.e. Cabin rises at 2-300 fpm from takeoff whilst aircraft is climbing at 2-3000 fpm, but the principle is that there is some pressurisation all the time so I doubt that anyone could open a door
Many emergency exits are plug type exits as well so the pressurisation effectively holds them in place even if the latches are released, so again it would be a physical challenge to get an emergency exit open.
So all the terrified, my life flashed before my eyes, reports from punters when someone pissed or on drugs leaps up and starts fiddling with the door handle are a bit on the melodramatic side, though in fairness they aren't to know.