Thanks for the input.
I'm sure part of it is little kid, but its obsessive, even for a little kid. If his whining and crying had worked for him even one time in the past years, I could understand it, but he's never gotten to open a present early, yet it continues. I mean, our tree is down, gifts put away, etc etc etc, we don't see this sitter anymore, there are no "reminders", yet it is constantly on his mind. He only *cries* 3 or 4 times a day, but it comes up hourly at least, and was all he would talk about until we started walking away when he talked about it (he'll cry about it, tho, whether we're in his presence or not).
I don't know if he's Autism Spectrum Disorders (ASD) or not, half his team says he is, other half says he's not, but he toes walks, hand flaps, beats his head agains the wall/chair/seat, does not read facial expressions AT ALL, and obsesses over more than just gifts - can't say the signs aren't there.
His gift obsession has nearly ruined the holidays the past years he's been big enough to be aware of what's going on. He knows the tree can go up at Thanksgiving (thank you blaring tv commercials) but we don't put presents under it or talk about gifts or exchanges or even Santa anymore because this is where we end up. (and on the Santa note, he hears songs or people asking him if he's been good this year and he ends up in a heap on the floor because, as he says, he's so bad - so the Santa that comes to our house is not a judge of character or behavior - he comes to all). But once difficult child finds out there are gifts for him, it is a constant battle (literally constant) to get him to focus on anything else. Its the first thing he says when he wakes up in the morning, comes home from school, its just all the time.
Our gift to the sitter and her kids is dinner out and I'm taking her kids for a day/evening at the playplex (not McDonald's playplace), so there's nothing to unwrap and we've already told them. But she knows difficult child and how he can be, so I just emailed her and explained what was going on and asked if we could get together soon. She's a good friend, she knows difficult child as well as anyone (she was the first one who talked to me about him having some "issues"), I think she'll understand.
A little positive spin on my wee difficult child, tho - when he woke up Christmas morning and found what Santa left under the tree for him, I watched/listened from my room for a while...he looked at each thing, and after the initial marveling, would look to the ceiling and say "Thank you, Santa" for each thing he was given.