Playing these very small because they are considered sucker bets.
A round robin bet is a series of parlays combined with at least 3 teams. For example if there is team A, B and C. Parlay 1 is teams AB. Parlay 2 is teams AC. And Parlay 3 is teams BC. This makes for higher payouts when you win. Parlays pay out roughly 13-5 at -110 odds.
The downside to this is you have to win at least 2 of your 3 picks to profit.
3-0 = + 7.8 units (roughly)
2-1 = + 0.6 units (roughly)
1-2 = - 3 units
0-3 = - 3 units
Since it's baseball season the odds won't always be -110. So I'll be using a lot of 4 teamers as well.