Thanks guys! My sister got me birthday balloons, so many that I had to put most in the trunk and cut the big one off and put it in the back seat to get it home, then retie it onto the bunch. Some of the rubber balloons are already losing height, but the mylar ones are still Birthdaying in there.
Rubber balloons sagging in sag order (none have lost their plump yet, just not hanging as high):
white with color swirls
purple with happy birthday tampo
Rubber balloons NOT sagging yet:
3x green with happy birthday tampo
pearly dark blue
red with tampo
pink with tampo
Weird, huh? Also, they're kinda undulating in the air conditioning stream.