Despite what cartoons might make you think, one hard pull does not an Atomic Wedgie make. To get the back of the underwear to stretch from the butt all the way to the head depends on the material the underwear is made out of and requires continuously pulling on the fabric to stretch it out but not enough to rip it.
Grabbing at the waistband will most likely end up in the waistband being ripped off from the rest of the underwear, if you want a non-ripped over-the-head Atomic Wedgie youll need to go for the leg holes. Stretching the leg holes as high as they can go means the fabric attached to the waistband gets put under less strain and is less likely to rip apart.
Atomic Wedgie tips for selfers: If you feel like your forehead needs to be acquainted with the Tuesday written on the back of your waistband youre going to need to receive a couple of wedgies first. A Hanging Wedgie