Bacon sandwiches, a staple of British builders the world over, are the easiest and most nourishing/filling of all hot snacks that:

a) do not come in plastic packs with symbols vaguely related to microwaving

and

b) take roughly 10 minutes to make.

For the simplest bacon sandwich (and, IMHO, the tastiest) follow these simple instructions...
  1. Get TWO rashers of bacon. One is too little-three is too much. TWO.
  2. Fry the bacon. Do not grill it, fry it. The health benefits do not outweigh the taste benefits...trust me on this, OK? Don't use olive oil, vegetable oil leaves a purer taste.
  3. While the bacon is frying, apply ketchup to the bread, or even better barbecue sauce. Do not taint yon sandwich with anything that was at some point a green plant or attached to a green plant (apart from, of course, the bread and the sauce) or butter. Butter does not taste good with ketchup! At all!
  4. The bacon should be done now, so give it a little bit of mayo on top. Yes mayo. Mayo + bacon = fun treat, so just spread a little bit on the bacon. Thus, you do not get mayoless bacon or baconless mayo.
  5. Place bacon upon bread. Close up sandwich.
  6. Eat, and wash down with a shandy and liberal doses of Butterfinger McFlurry.

Gorgeous.

Just remember:

Public transport companies will fob you off with a roll with a thin rasher of bacon inside and a splodge of ketchup! This is not a bacon sandwich, this is a culinary abomination! Avoid like the plague.