The Over / Under 7 Bets
The Over/Under 7 Bets are not all the common in casinos, but gamblers will find them on occasion. The Under 7 Bet is placed on whether the next roll is going to be less than seven. That means that the wager pays off if a 2,3,4,5, or 6 is rolled. The Over 7 Bet is placed on whether the next roll is going to be over a 7. That means you're betting on whether the next roll is an 8,9,10,11, or 12.
Notice that either of these wagers lose when a seven is rolled. This is a key factor, because it weights the odds heavily against the bet winning. The house edge on the Over/Under 7 bets is 16.70%, making it one of the worst sucker bets in craps. This also explains why this wager is not seen very often in casinos.