It's everywhere you look. Not only on the computer, but on flyers, shirts, signs - even restaurant menus. Sometimes it seems like the spawn of Satan, ...oops, I meant Comic Sans MS, is taking over the world.
Unfortunately, I have come across many sites that use this atrocious font, which makes me want to pick up my monitor and throw it across the room (okay, maybe not...but I at least want to shield my eyes from the horror that is Comic Sans). What makes it even worse is the fact that it's usually in some neon shade of yellow against an aqua background. Or it's scrolling across the page at 90 miles per hour in size 72 bold. Even when it's at a normal size and a decent color, Comic Sans makes your site look n00b-ish. Hopefully if you're trying to make a site that's worth visiting, you're not a n00b. When I see Comic Sans I think of an annoying preteen kid on an AIM chatroom saying "LOLZ HAI CHECK OUT MAH PICZO! MAH NEW WEBBIE PWNS J00! LOL!" in hot pink. You don't want your visitors to think that too, right?
So if you're not in preschool anymore, which you most likely aren't if you're using the internet, it's time to move on to a better font. Unless you want people to think you're a 5 year old who watches Barney every morning and spends hours filling in every page of your coloring book, avoid using Comic Sans. There are much better default fonts out there - Tahoma, Arial, Verdana, and Georgia, just to name a few.