My brother takes the dice and rolls the point. Everyone places their chips. I place my chips. The dealer asks me, “Did you mean to put your chips on the Don’t Pass Line?” “Yes, that’s exactly what I meant to do.” Silence. Then my sister: “You’re an asshole.” My brother rolls again: seven. The Don’t Pass Line wins me a couple bucks.

This doesn’t make any sense

1. Once the point is established by the shooter on the come out roll, you cannot play Pass or Don’t Pass lines.

So after your brother takes the dice and rolls the point. You cannot place your chips on Pass/Don’t Pass. Maybe why dealer was confused?

2. Don’t Pass Line pays on shooter rolling 2 or 3 on come out roll. You’d lose if he rolled a 7. Pass Line wins if shooter rolls a 7 on come out roll.

Second roll was a 7?

You’d have bet Don’t Pass before your brother ever rolled the dice for a second roll 7 to win the Don’t Pass

Bets after the shooter’s first come out roll are usually Come/Don’t Come bets.

If you made a Don’t Come bet instead of a Don’t Pass (Dealer was confused from your illegal play and considered it a Don’t Come bet.) You’d still lose if a 7 were rolled second. So that doesn’t make sense.

If your first bet was after your brother rolled once. The only way you’d win with him rolling a 7 on his second roll would be to play a SEVEN bet. Which would be an even bigger dick move than Don’t Pass because it’s a one turn bet that your brother was going to roll a 7.

I guess most likely you played the don’t pass before your brother ever rolled