I still remember the first time I got high. Couldn't stop laughing for about half an hour. Everything was funny.
After a shit day at work, it's so easy to get pissed off at your room-mates over the pettiest little things. A dirty kitchen, a trash-bag, a bad light bulb, a leaf on the floor - everything is annoying.
All it takes is a few deep puffs and none of that matters. Seriously, the world would be so much more peaceful if people smoked more weed.