They're not doing it just to give their followers a thrill. OK, so they may be giving some of their followers a thrill, but they're also raising awareness for male breast cancer in the process. 

47-year-old Hulk, Mark Ruffalo is just one of the celebs highlighting the campaign by posting a topless shot of himself to twitter...

Seemingly Mark was motivated to do the shot by campaign spokesperson Samuel L Jackson.

Jackson narrates the below video, which teaches you how to check your set - as more men die of breast cancer every year than you may think.