• Gasbags: Even when doing nothing else, humans are constantly sucking in and pushing out air.
• Slow rotting meat: As opposed to steaks which rot in a day, humans take a few decades to rot, but to a robot which might live for millennia, it's about the same
• Wet Brains: Unlike a robot, our brains are wet, mushy things.
• Sleepers: How weird must it be to see a lifeform that spends 1/3 of its short existence unconscious.

But, I can also imagine words of admiration from robots for things humans can do that they can't, for example:

• self-fixers: When a robot part breaks it needs to be repaired. With a lot of injuries, humans just have to wait and the body repairs itself. That would seem pretty magical.
• puzzlers: Humans are capable of lateral thinking in a way robots aren't. Humans can use analogies to things they do understand, and can reason about things in the physical world.
• stinkers: Could be an insult because of humans pooping, pissing, sweating, etc. But it could also be a play on "instinct", somehow magically making a good guess about what to do in a new situation that's outside their "programming".
• leaders: Robots are good at responding to inputs, but they don't actually have any motivation themselves. If eventually there's a robot that's capable of thinking and wondering, it might wonder what it's like to do something, not because someone asked, but because you wanted to do it.