**Let's go on ahead and exercise that inner jerk now shall we?
Order a VERY big meal, like a quarter pounder meal with twister fries, upsized, some and a strawberry float. Have it for dine in, and then look for a very large person preferably eating alone. An is ideal; men just don't care about their fat asses or screaming waistlines as much as women do. Also, what she's eating counts: if she's indulging herself on a meal that's just as killer as what you're having, then forget it. Look for a large person who's eating a small meal, maybe a sprite and some fries no ketchup. Sit next to her, preferably opposite her so you can watch her... squirm. I suspect this to be the natural reaction when you're killing yourself on a while there are people who don't have no need for such narcissistic bullshit however healthy.
It's not my fault that I have a metabolism that creates sonic booms - so fast it breaks the sound barrier. It's a gift. It's not a super power meant to save the cheerleader, and then the world in consequence. Its not stopping time or walking through walls, and you can't imagine how such a blessing can be put to good use, so you might as well try to have fun with it. Which is what I'm doing. Now, it's important that this obese lady you're sharing a seat with knows what you are eating. Discretely look out for some semblance of acknowledgment, like an occasional glance from her at what's on your table. Feng shui counts, so make sure that your meal's well spread out to attract attention. Red sells, so you might want to have your nuggets, fries, and the strawberry float closest to her. Wait for her to steal a glance or two, and then go for the kill.
Eating, on its own, doesn't heighten the effect we're after. You will need to throw in as much theatrics as you can manage as you are indulging yourself in your heart attack lunch. Pick up your quarterpounder in one hand, hold it parallel to your face, and then slowly unwrap this meaty killer burger. Enjoy a few bites, love it!, before paying attention to your fries or nuggets, whichever you prefer. But the trick here is the ketchup. Take your half eaten quarterpounder down as you reach for a packet of ketchup. You know where to put the burger down (as visible as possible). And then, with the production value of a slow motion scene, proceed to bite that packet open, waay open such that it takes you about a few seconds to help yourself. However you garnish your burger is totally up to you, but we're after that great big pause.
Now, no matter what happens, try not to look at the subject of your torture. That totally defeats the discretion we're after. And that's just outwardly rude to begin with.
Pictures from here and here.