Whenever a producer puts together an ensemble cast - especially on sit-coms - one of the characters is bound to be "the dumb guy." Woody on Cheers. Bull on Night Court. Joey on Friends. Even Michael Scott on The Office. It's a good character because it's kind of a sounding board for the audience's reality. But it's also cliche.
A few years ago (before he killed his career), I read an interview with Michael Richards, who played Kramer on Seinfeld. He said that he really came into the character in about the third season. He said it dawned on him that Kramer wasn't slogging a few paces behind the rest of the cast. He was wildly racing blocks ahead of them. If you watch the early Kramer vs. the Season 4 Kramer and beyond, you see what I mean.
Kramer was still filling the role. Technically, he was the "dumb guy." But the blocks-ahead-vs.-steps-behind approach made him unlike any other ensemble cast "dumb guy" ever seen, and one of the most memorable characters on TV. And it's because he took the cliche and turned it on its head.
I bring this up, because turning the cliche on its head is a great tool for you to use. If your CD or a professor points out that one of your ideas is cliche (chances are, you know already), don't immediately abandon it and rack your brains for a replacement out of thin air. Start by admitting that you used a cliche for a reason, so on some level, it works.
Take that cliche and turn it on its head. Kramerize it.