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.
To verify your identity, we typically request one or more of the following.
1
A current (non-expired) Government Issued Identification Card, such as: State Issued Driver's License. State Issued Identification Card. US Passport. ...
2
Picture of you holding your ID, with your face visible in the image.