Ayew knew he was on a yellow and was stupid to commit a deliberate foul. When Dunk was stupid and swore at the ref, most of us, including our manager, admitted that Dunk had been stupid.
Commentators have been bleating, but Palace have been using the 'foul to stop a counter' tactic the whole game and for once the ref's had the balls to give the standard yellow card for the offence to someone who had already been booked.