Agencies can be a fun place to work, but some days—namely Fridays—they can also be a bit of a powder keg.

Whether it's a poorly timed joke, an overly vague bit of client feedback or just a boneheaded moment of Rubeus Hagrid-level regret, one unfortunate comment can often ignite flames of hatred that occasionally smolder for years to come.

We asked veterans from many of the agency world's most common occupations to share their least favorite types of comments. So check out some of our favorites below, and be sure to let us know if you have your own suggestions for phrases to avoid.

To a Copywriter: "I hope you didn't make plans this weekend."

To an Art Director: "Hmm, it just needs, I don't know, more pop, you know? Like, more (makes waving hand motions) crackle to it. Cleaner, maybe. Oh and these partner logos need to be added, and brand standards require they run green on black."

To a Creative Director: "Oh, you mean like the thing Old Spice did?"

To an Account Executive: "Then tell the client they'll just have to live with it."

To the CEO: "Did you see that big article today about [rival agency down the road]?"

To a Media Planner: "Can't we just take it from the discretionary budget? You guys always have a discretionary budget."

To a Media Director: "We're thinking full-court press: Mobile, social, TV, outdoor, viral. We really need to get everything we can from this $125,000."

To a New Business Manager: "How important is this pitch?"

To a Producer: "What do you mean we can't license the song? The client already approved the rough cut. Just make it happen."

To a Project Manager: (On the way out the door) "Oh that? I didn't get around to it."

To a Video Editor: "The client's son is in film school and has some ideas. He says you can just send him the raw files if you're not up to it."

To a Developer: "The client's expecting this to work across all the platforms: mobile, Android, Facebook, .NET, watches … you know, all of it. Just keep it flexible and be mindful of the budget."

To a Production Director: "I'm pretty sure I would have noticed this kind of error on the proof. Surely they'll redo the print run if you tell them it was their fault."

To the CFO: "So I was cleaning out my desk, and I found some invoices."

To the Receptionist: "You should smile more." (See footnote below.)

To a Strategist: "But I'm a millennial/boomer/shopper/parent, and that's not how I feel about brand loyalty."

To the PR Director: "Then why didn't sales go up?"

To a Social Content Planner: "Man, I wish I got paid to play on Facebook and Twitter all day."

Footnote: The receptionist comment elicited our favorite moment of vented frustration. "A serious downside to having a front desk gig is mofos expecting you to have some kind of crazy Joker-esque grin 24/7. God forbid you have resting bitch face. Not that I'm bitter."

Got any to add?