Would you question her sanity if...?

My 59 year old mother in law recently got her nose pierced. The woman has always been a little on the crazy side (i.e. she curses profusely around her grandkids, she plays favorites with her children/grandkids, once I caught her son giving his 9 month old son a drink of his beer and her response was "oh it was only just a little"). Now, she calls to tell us she's gotten a nose ring. Is it bad that I do not want my kids to be around this woman unsupervised? I feel bad but she is a hamburger short of a happy meal and she does not see that her judgment is not great. She doesn't think she's crazy but she laughed at one point when she kept our 1 year old daughter and my daughter had climbed on top of her piano. She could have been hurt and the woman is laughing!!! Any suggestions on how to handle this situation and let her know that I am not comfortable with her keeping my kids from time to time???