I have a post office box, so for me, it's opening the box and finding a lovely yellow "you have a package" slip. If the box is full of mail, it's like an Easter egg hunt. Yellow, yellow, where's the yellow?
Then, I get to wait on the line, wondering if it's the Xtol from B&H, the film from JandC, or some little thing I picked up on eBay two weeks ago, and have completely forgotten about. When the guy or gal brings the box in from the back room, I have about 10 seconds to figure out what it is from the size and shape of the box, before I can clearly read the return address.
Yeah, I'd say I'm still a kid!