A 2-7 offsuit hand is the worst hand to start with in Texas Hold 'Em poker because there are so few good options available to you: you have no straight draw, no flush draw, and even if you wind up with a pair of 7s or a pair of 2s, you're unlikely to have the best hand.
One of the first things you learn in poker is that 7-2 offsuit is the worst hand you can be dealt. It doesn't easily make a straight or a flush and when it makes a pair it is usually dominated and/or outkicked. So you should never play 7-2 offsuit, unless it is during the 7-2 Game.