I am not now nor have I ever been much of a swinger. However, I do know Omni.
In the few jurisdictions where it is offered (I don't know of any in the US), if you bet the Omni, you are selecting two horses. If both of those horses finish in the top 3, then you cash. Obviously, there are three possible Omni winning combos.
For example, if the top 3 finishers were 5,9 and 3, the Omni would pay for the combinations 3/5, 3/9 and 5/9 in any order. Because there are 3 combos and you don't need to hit in exact order, the payoffs are smaller than an exactor and probably smaller than the seldom played quinella. It is my understanding that each payoff is based on the amount wagered on that combo, so all 3 payouts are likely to be different.
And no, I've never played it.
