Attending: "Can you cut me a small piece of tape?"
Med student: [cuts very small piece of tape]
Attending: "No, that's too small."
MS: [cuts microscopically larger piece of tape]
Attending: "That's still too small."
MS: [cut much bigger piece of tape]
Me: "Now that's TOO big." [pause] "Just kidding."
I will never get to be a surgeon, so that was probably my only shot to make that joke.