A result like this means that you bet your $100 on a money line (ML) of -120 -- $100/1.20 = $83.33. The Super Bowl ML was more like -135 on Green Bay, so specifically, our guess is that you bet a point spread with an amended money line -- probably Packers -2.5/-120. Here's how that happened.
The packers opened as 2-point favorites and quickly went to -2.5. The line stayed there for several days and you could get -2.5 at the standard bet $110-to-win-$100 arrangement. However, as it got closer to game day, the Packers moved to -3 in most places. Some books continued to offer -2.5, but with an increased lay price -- namely $120 to win $100 -- which is probably what you bet.
The second force at work concerns betting to "risk" as opposed to betting to "win." It would be much more common to bet $120 to win $100, but the computer will make the calculation for any wager amount. If you walk up to the window and say "I want Packers -2.5 for $100" (or just give the number from the board that corresponds with that bet), most ticket writers will ask, "Do you want that to win $100?" and at that point you can decide. But some writers don't care and will simply take the bill and punch a $100 wager into the system, which spits out a ticket indicating a bet of $100/$83.35.
When betting online, most systems have "to win" as the default. So if you type in $100, it displays $120/$100 unless you specify that the amount entered is what you want to risk. Bottom line, you have to be precise and pay attention, or you're stuck with what comes your way.
