If you follow Jeff Cooper’s rules, it violates 1 and 2, maybe 3. If you follow the NRA rules, it violates 1, maybe 2, and probably 3. Either way, Mas Ayoob shows us what happens when you violate the rules.
Note: Mas’ article has some pictures, which aren’t that pleasant to look at… not too bad but bad enough… hopefully it’ll burn the image into your head and reinforce the importance of following the rules.
Stuff From Hsoi 
Yep, I have seen people do this (minus the near amputation). In fact, there is a product out there to make it more comfortable.
http://www.midwayusa.com/Eproductpage.Exe/showproduct?saleitemid=324052
Still, I’d rather get my toe blown off than my head. I’ll give them that credit.
So does it make it more comfortable before or after you blow your toe off? 😉
I dunno. Just seems that no matter how you slice it, it’s rule violations. Unless I guess, your toes are something you’re willing to destroy.