I just need to vent a bit

I was having a good morning, I still am, but I'm just a bit ticked off. I just went out and retrieved my mail and there was a letter sized envelope addressed to me, with the return address from someone I've never heard of. So, yeah, okay maybe I obsess a bit over my unopened mail, but I don't like surprises.
Opening the envelope I find an invitation to a baby shower, for someone I barely know. It's the wife of one of my husbands' childhood friends, the only communication we have is the annual Christmas card.
First let me state that I HATE showers of any kind, wedding, baby, it doesn't matter, to me it's just another way to get a gift and to make women play stupid games. People, there is a reason men aren't involved with showers and that's because they wouldn't put up with the nonsense of them. "Here put on this stupid baby bib with your name attached and see how many words you can make out of 'baby puke', and if you get the most words you win this candle we got at the dollar store half priced". (and no i never put any one through a shower of any kind for me)
Second, do they really think I care that they are having a baby ? I mean, it's great if that's what they want, but I hardly know these people and now they expect me to fork over a gift. Is it me ? Am I being unreasonable ? Do I have to RSVP if I'm not going ? Will Ralph expect me to attend this event ? Am I obligated to send a gift even if I don't go ? But the biggest question I'd like answered is this, who was the one that invented this custom of showers ?
Yep, I really, really hate showers, can you tell ?