Donk is a (potentially offensive) term used to describe a very bad poker player. A donk bet is a bet made out of position after check/calling on the previous street. The link here is that it's usually 'donks' who donk bet hence the name behind the bet.
An up-and-down bet involves two selections and two separate bets on both those selections, in each of which the second bet is conditional on the first one winning.
Many casinos in Florida have started running sports betting, craps and roulette. Florida is now the largest state offering online sports betting, but some hope the courts will still step in to stop it. The stakes are high for the Seminole tribe.