Etheridge has already saved three penalty kicks this season.
After stopping spot-kicks in each of his first two appearances in the competition in August, Etheridge then kept out James Maddison's second-half penalty at Leicester City in Cardiff's 1-0 win last week to move to within one save.
Cardiff have conceded a joint-high five spot-kicks this season, so Etheridge has had enough chances to put his penalty-saving methods into practice.
"You try to put as much pressure on the strikers as you can," the Filipino said earlier in the season.
"To be honest, it's not easy at this level, they put the ball where they want to. But you make yourself big and stand as long as possible."
If he does have to face a penalty against Huddersfield Town, Etheridge's attempts at mind games will probably be helped by the fact that it will be his opponents' first spot-kick this season.