These lines are actual lines from Military Performance Appraisals:

1. Got into the gene pool while the lifeguard wasn't watching.
2. A room temperature IQ.
3. Got a full 6-pack but lacks the plastic thingy to hold it all together.
4. A gross ignoramus -- 144 times worse than an ordinary ignoramus.
5. A photographic memory but with the lens cover glued on.
6. Bright as Alaska in December.
7. Gates are down, the lights are flashing, but the train isn't coming.
8. He's so dense light bends around him.