Definitions by Herman D. Optional

Mediocre

Not good, not bad, but a negative term nonetheless. Often used to describe something that is average, but was expected to be much better.

She was a mediocre student who could have been much better.

What someone who is clearly defeated in an argument will say to try and end the argument before being beaten even more soundly.

Greg: And that, dipstick, is why rocket shoes will never work.

Bryant: Don't talk to me, loser.