Firstly..... why have I never heard of this before? If it's real then 'OOOOOWWWWWWWWWW'.
Secondly...... definitely not for the squeamish, it cannot be unseen, I may unclench again some time in March! Don't blame me.
Thirdly........ Common household glass objects aren't intended as toys, maybe it's better to do a bit of online shopping for your extremes than have to explain some nasty lacerations to the nurses, doctors and observing medical student group in A&E. Look for the kitemark folks :shock: