They might have been talking about another new guy. Don't put yourself down so much OP.

Just quit and find a new job. Or stick it out and show them that you are worth keeping. There's two solutions to every problem.

Prove them wrong...do the best job ever on those "shit-tasks" and they'll see you're smart.

Here's your chance to prove them wrong. Be a total badass and make them feel shitty.

See how it goes first before making any rash decisions. Certainly don't do anything impulsive based on what you overheard until you've at least confirmed they're talking about you

It sure is a good thing at least you're not the new guy... Er.. Wait

Sometimes it's good to be underestimated?

Well you are the newbie. It can be hard to intigrate into a new workplace, there will already be a pecking order and cliques. You have to stick it out and prove that you can do the job and get to know people. Work through the shit and when they start to respect you and see you aren't going anywhere they will give you better work.

well, thats awkward

So what did/didn't you do that they think you don't have smarts?