It was something of a joke, but the way you do that is to drop off the card to the hostess with apologies but thinking you just don't want to risk exposing the mom to the flu, plague, a herpes attack. Whatever.Um, how does that work? If you mail it to arrive around the day of the shower, then your planning your sickness. If you call in sick on the day of the event, then the gift card makes it look like you totally forgot to begin with and sent it later as an afterthought.
Don't tell me guys don't use little white social lies to get out of doing something they don't like.