stupid mistake

i'll start off by telling one of the many mistakes i made when i first played in a casino, then if you guys want, you can tell about some of your stupid mistakes.
3/6, i bet with a flush draw and a few seats over a player asks "who bet? the 14 year old?" this guy is a douchebag wearing a rolex apparently, playing 3/6? come on.
anyway, i say, "yea the 14 year old bets, are you gonna fold to a 14 yr old?" he calls and the turn brings the heart i needed for the ace high flush. i bet and he calls. river is a blank, and i say, "let me check my cards" and look down like i forgot what i had. when he hears the word check he says check and shows down his hand. at that point i objected and said i wasn't technically saying check, i used the word in another context but to make a long story short, i lost an opportunity to win an extra bet with that stupid move. i learned my lesson, be careful what you say at the table, and think before you try to make a deceptive play like that.

i am playing 1/2 nl last weekend. it's about 2 a.m. at the end of about an 8-hour session and the boar hits AQQ. i'm holding KJ, and a guy bets a pretty small bet, and i call(the first dumb part) knowing if the T hits, i'm going to take his stack. i am 99% sure he is holding a moderate A. anyway, i hit the T on the turn and i call another medium sized bet waiting to raise on the river. anyway, an innocent looking 7 hits on the river, and he goes all in for about $100. i instantly call. i am ready to take in the pot when i notice he turns over the nut flush with A4. i was tired and excited, and i haden't even noiticed that the river was the 3rd heart. that was one of my top 3 worst poker moves of all time.