Lots, but the most recent was probably on Wednesday when I was playing Silent Hunter III (with The Grey Wolves mod). I had been stalking a convoy for a couple of game-time days, come close enough to risk being spotted by escorts once or twice but had gotten away with it.
The order comes (after other U-boats had been ordered onto the convoy too) to attack the convoy, so I spend an afternoon of game-time positioning myself ahead of the convoy and as dusk falls, I dive the boat. As the phalanx of ships starts to pass overhead, I come up to periscope depth, raise the attack periscope, and smack bang in the middle of the convoy about 1,500m ahead I see a Revenge class Battleship in the perfect position for a full spread of 4 torpedoes. The first three missed or were duds (lots of duds early on in the war) but the 4th must have gone off near a main magazine (damage modelling in the Grey Wolves mod is far superior to the vanilla modelling in any SH game imho) and the damn thing just blew up about 10 seconds after the initial impact.
Cue half a dozen or so thoroughly pissed off escorting destroyers charging into the convoy, every searchlight that could be brought to bear sweeping the water looking for foam, periscopes or torpedo wakes and a swift dive as deep as I dared to creep away and think about the long trip home (one torpedo apiece in the fore and aft torpedo rooms is really a purely defensive load) while they thunder around in circles. They never did find me, but my hydrophone operator reported more explosions and breakup noises - whether they were from torpedo attacks by other U-boats, or from collisions (they happen!), I never did find out...
Bloody epic game if you have the patience for it ^_^