That's because customers try things on, it's most likely not the stores fault or the supplier. This is why you should wash anything you buy before wearing it.

Lice*

Bye bye life - you were gone so soon! ?

I wish I had known about the life remover packets.

The word today is just a formality on this site for posting an fml. Read the guidelines.

crabs....

It's really not the store's fault. Unfortunately, loads of people have lice and aren't aware of it (yet), or don't get proper treatment soon enough. Lice really don't survive for a long time when they're not on someone's head, you'll usually get them through actual physical contact with someone else (which is why kids get them easily, they tend to be in close physical contact with other kids while playing.) When you try on a hat that has been tried on by somebody who has lice, say, an hour ago, there's a chance that some of the lice stayed in the hat and might get on your head. This can really happen anywhere where a lot of people try on hats, OP just had bad luck, there's not much the store can do to change this.