It's an instance that seems to appear out of nowhere, but isn't a stranger. The occasion takes place and you mentally" add it to the list." It might be completely harmless, it might be vengeful, and it might be plain old rudeness. Regardless of the motive, it happens.
Clients will often say certain things to designers that make us cringe. It's time to spread some education.
1. "Can you make the text more exciting?" / The term exciting can be interchanged with any adjective, really; cool, organic, formal, etc. Vague words only waste time. If you have an idea, be honest about it. You can save time, money, and maybe some bad words spoken about you behind your back.
Just kidding about that last part.
2. "Have fun with it." / I absolutely CANNOT stand this phrase. I know you've all heard it. My experience has shown me that this is a general string of words that means, "I don't have any idea what I want." If it's the off chance that you CAN have fun with it and they accept it and love it every time, then you should ignore this and never leave your job. Ever.
3. "I don't know what I want, but I'll know it when I see it." / Actually, since I'm a mind reader, I know exactly what you're looking for 100% of the time, so I take this back. Good times.
4. "Is there a reason you did this?" / This sentence can come in varying ways. But it should be known, there is a reason I put something somewhere. If I were haphazardly throwing design elements around, I'd probably be the same person using Comic Sans for the important defibrillator sign.
5. "Can this go here, and this go here, and..." / Someone describing, word for word, an entire design layout for you to basically assemble can be mindless (and sometimes thankful) work, but if it's not the strongest or best solution for a design, it can be downright painful. It's a feeling of no control and sometimes shamefulness. I've denied my hand in projects because it's like doing color by numbers, but you're blind in one eye, and got your hand chewed on by a baby alligator.
Part of what it takes to be a designer is to successfully work with humans. And part of that work is combating some of these eye-roll-ful phrases. If you feel comfortable enough, go ahead and let the client know they need to be more clear, there is a purpose, and you have a potentially better solution; after all, it is your job.
If not, patience is power in every situation and I have learned it can be just as healthy to bitch with other designers.