Suicide by fapping

Disclaimer: I'm asking this question purely out of curiosity and do not have any intentions of carrying it out.

In theory, how many times a day would you need to fap in order to get yourself killed?  Assuming you're eating enough food, getting enough sleep, breathing acceptably fresh air, living in an acceptable climate, etc.?

Depending on how much of a lardass one was, a heart attack could be caused.  Or, if a person went at it dry, he could actually rub the skin off and eventually bleed.  Failing that it's possible cause a blister which becomes infected and kills you by blood poisoning. 

Other than that exhaustion is pretty much the only way a person is going to die from wacking off.