All glued up

I once worked with a lady who would do some very strange and very silly things. One of her finest mistakes was when she ordered some envelopes for the use of posting mail for the company. She was having some problems with getting the envelopes to stick after she had licked them. So she returned them to the supplier and got another box to replace. The same thing happened. So when she went to return them the suplier asked what had been going wrong. Once she explained that the glue was not working because they would not stick once she had licked them. This was when the supplier informed her she had been licking self sticking envelopes and had in fact been licking off the glue.