ONE: Go to YouTube.com and do a search for "prank." Say goodbye to your Saturday! (Alternately: search for "funny baby" if you're seriously depressed.)
TWO: Here is an enormous directory of online comics. Most of them are shite but there are several high-quality titles: it's up to you to find them. I could tell you which ones they are but many people prefer to feel they're in control of their lives.
Prior to the discovery of ohnorobot.com I only had one good method to stave off boredom.
Notice that you cannot "prevent" boredom, you may only "stave" it "off." Boredom is not like a virus that you can contract if you live irresponsibly; it is like an evil spirit or a cubemate's fart, against which you may employ special herbs or a fan. Boredom may also be "warded off" but only if you used to play AD&D or your parents lived in Salem, Massachusetts.