Start by building a charcoal snake around the outside of your Weber. Two briquettes as a base and then a third (making a triangle), and then run it maybe halfway around the circumference of your grill. Get some hickory wood pieces and stack them at intervals on top of the snake for extra flavor.
Get a 15 lb. Boston butt, or some similar, large, fatty piece of pork. Procure a nice barbecue rub of some sort or another, and rub that all over the outside. It’s not a bad idea to do this the night before and let it think about it in your refrigerator.
Place it on the grill. Keep it fat side up the whole time, and don’t even think about flipping it.
Get a thermometer in the grill (or if your grill has one, check it) — you want to regulate the vents so that you’re somewhere around 250 degrees. Put your remote probe thermometer into the meat, and smoke it until the internal temperature has reached 145F. That’s probably going to be something like six hours.
When it hits 145F, pull it from the smoker and take it toward your oven, which is preheated to 300 degrees. Wrap it up in a tent made from two layers of heavy-duty tin foil. Pour a can of Dr. Pepper in there with it if desired. Get your remote thermometer back in there and bake it until the internal temperature hits 195F.
A ten-page rambling Reddit thread prompted by Spyrulfire and I_AM_THE_LIQUEUR