"I can only do one thing at a time."
News flash: Complaining you are overworked will not make your boss feel sorry for you or go easier on you. Instead, a boss will think: (1) you resent your job, and/or (2) you aren't up to your job. Everybody, especially nowadays, feels pressured and overworked. If you're trying to be funny, please note that some sarcasm is funny and lightens the mood. Some just ticks people off.
"I am way overqualified for this job."
Hey, maybe you are. But the fact is, this is the job you have. You agreed to take it on and, while you may now regret that decision, it's still your job. Complaining that it's beneath you only makes you look bad. Plus, coworkers doing similar jobs may resent and dislike you. And guess what? Bosses will not think, "Oh, this is a superior person whom I need to promote." Nope, they'll think, "What a jerk."
"This job is easy! Anyone could do it!"
Maybe what you're trying to convey here is that you're so brilliant your work is easy. Unfortunately, it comes off sounding more like, "This work is stupid." Bosses don't like hearing that any work is stupid. Nor do they really like hearing that a job is easy peasy. It belittles the whole enterprise. If a task is simple, be glad and do it as quickly as you can. Even "stupid" work needs to get done.
"It can't be done."
Saying something can't be done is like waving a red flag in a boss's eyes. Even if the thing being suggested truly is impossible, saying it is can make you look ineffectual or incapable. Better to play detective. Why is the boss asking you to do whatever it is? What's the problem that needs to be solved? What's the goal? Search for doable ways of solving that problem or reaching that goal. That's what bosses really want. Most of them do not expect the impossible.
Last words : When in doubt, remember that silence really is golden.
Concluded
Source : DSDG Email