Okay, I don't know if this counts as a "snack" or lunch or "brunch" or what, but it is very tasty!
(serves 1 but multiply everything by the number of people eating)
1. Hard boil 1 egg
2. While the egg is boiling, dice a small tomato and lightly toast a slice of your favourite bread (if you didn't use your grill (broiler?) to do the toast, turn your grill on to pre-heat)
3. Shell the egg and put it in a bowl. Mash it well with a fork.
4. Throw the chopped tomato and 1 dessert spoon of mayo in with the egg, season to taste (don't add much salt unless you like things really salty, but lots of fresh ground black pepper) and mix
5. Pile the mixture on top of your toast, smooth out, and put under a medium grill for a few minutes (you want to heat the mixture, not brown or burn it, so this is no time to leave the kitchen!) About 2 minutes should do.
Toastily tasty!