Irish moss (thing)

Irish Moss is a traditional Jamaican beverage made from seaweed extract, whey, nutmeg, tumeric, and other "secret" ingredients. In its most potent form, served chilled and mixed with rum--that Caribbean social lubricant--Irish Moss is said by the locals to be good for de back, i.e. promoting masculinity and--by extension--sensational sex.

It is and it does.

It's also legal.