Seriously!?

My six year old brought home a birthday party invitation TODAY for a party that is on SUNDAY afternoon!! I like to think that I can go with the flow with many things but receiving invites this late to a birthday party irritates me a bit. In order for him to go I am going to have to figure out transportation to the party as Rob will be at work and the two youngest will be in the middle of napping and we will need to shop for a birthday gift sometime in the next 24 hours. The real kicker . . . the invitation actually requests an RSVP! Are you kidding? Although I understand the desire to plan (HA) and know how many are coming, if you don't have enough time to get me an invite with more than 48 hours notice, do I really need to respond as to whether I am coming?