Beginner and intermediate Limit Texas Hold'em players often make the mistake of playing any two big cards or any ace from an early position, and of calling raises with the same types of hands.
The problem with doing this is that these hands can so easily become trap hands.
A trap hand is any hand that has a high probability of becoming the second-best hand, costing you a lot of money if you flop to it. The most common trap hands are A-T, A-J, K-Q, K-J, K-T, Q-J and Q-T.
Many players limp in from early position and call raises in middle/late position with this type of hand. Thus, if you limp with K-J from early position, and someone in late position raises it, you could easily find yourself trapped against common raising hands such as K-Qs, A-K, AJ-s, AA, KK and QQ.
This also applies when you call raises with this kind of hand. This is a mistake. The most frequent raising hands from early position include AA, KK, QQ, JJ, A-Q and A-K. Why would you want to call a raise with a trap hand when the raiser is likely to hold one of the above hands?
Nonetheless, trap hands are playable in the right circumstances. For instance, if you are in late position and are first in, the trap hand now becomes a raising hand.
We recommend all beginner and intermediate poker players use a poker odds calculator to get some help identifying which starting hands to play.