Depends on what the topic would be.
But odds are, House would get really irritated by Sheldon after a while, while Tony Stark and Sherlock Holmes would probably be trading insult. Jack would be stumbling around looking for rum at some point and after House downs a couple of painkillers and stumbles off angrily having just given Sheldon a black eye, Sheldon would make some sort of comment about Jack using alcohol has a means to cope with his existence as a pirate, "an utterly useless and meaningless profession which romanticizes lewd behavior, wanton destruction and vandalization of other people's property and sailing in an inhospitable environment on a floating wooden coffin, crammed in with other bitter, disillusioned psychopaths such as yourself with only the promise of vast riches and 'lusty sea wenches.'"
...To which Jack would reply by shooting Sheldon in the chest. As he falls to the floor, a look of shock and surprise plastered on his face, as if Jack just pooped in his spot. Both Stark and Holmes would immediately rush at Jack to confront him, as they both are sworn to help people in their own way. House would hobble back into the room and start mumbling about Sheldon having a spastic colon, to which Holmes would reply, "No, it was a gunshot... we all witnessed it," and House would retort "Then you're as stupid as you are British..." then pull back Sheldon's shirt to reveal that there was no apparent gunshot wound, only a small mark on his skin, just above where the large intestine starts. Everyone would look around dramatically... Commercial.