If you look at mascots, you can find some goofy characters, who are extremely popular. A mascot does not have to be serious, it can be silly.
It really depends on your demographics. Who do you cater to? family
? corporate? kids? business?
If your site is dedicated to the business community, then a goofy mascot may not work, but if it is dedicated to families, then a silly/goofy/funny mascot might be a great fit.
Opening it to the public may bring in some crazy ideas, but some of the most successful mascots are probably way out of the box