Then there's the parents who figure that if they ever tell you that you did something well, you'd either [A] turn into a total slacker or [B] develop such a case of the swelled head that you wouldn't be able to walk through normal-sized doors.

Best one my dad ever pulled on me: back in the day when SAT scores were Very Important to most universities, I got 787 out of a possible 800 points on the verbal/language arts section. This is the 99 point something-th percentile. When I showed the paper to my dad, his only comment was along the lines of "How'd you miss the other 13?" He wasn't joking.