The only bummer about avocados is the browning. It happens once the flesh is exposed to oxygen because of a chemical reaction with the fruit's enzymes. Luckily, it can be prevented in several ways, and no, leaving the pit in the avocado doesn't work.
If making something, like guac, that also contains citrus, squirt lemon or lime juice on the exposed flesh immediately after you cut the avocado open.
But sometimes you don't want tart avocados, and that's when you use the boil method. Dunk avocados into boiling water for 10 seconds EXACTLY, then transfer to an ice bath to cool. This is long enough to kill those pesky enzymes, but not long enough to actually cook the avocado. Your avocado won't turn brown for several hours, even sitting out in the open air.