A chicken wing in pickleball is when the ball is hit to your forehand side, but instead of taking it with your forehand, you lift your elbow up really high and take a backhand.
Here's an image from pro Zane Navratil's video to help you picture it:
While this allows you to get to the ball with the paddle, these shots should typically be avoided because they are often weaker than forehands, and they can be harder to control.
They also give your opponent a spot to aim for the rest of the game.
Here's how you can avoid chicken wings creeping into your game:
Keep your paddle more neutral
Most players who hit chicken wing shots sit backhand too much while at the kitchen line. The back of their paddle face is completely open to their opponent, reducing the chance of them turning it to their forehand during a quick exchange.
Instead, players should sit more neutral or lean slightly backhand.
With this ready position, you can turn to your forehand more easily.
Slide then hit
Another way to avoid being chicken-winged is to slide your body to the left (if you're right-handed) or right (if you're left-handed) as you open your forehand to hit the ball.
If your opponent has shown a propensity to attack your forehand side, sliding and keeping your paddle in the hitting zone can help you counterattack more effectively.
This requires a bit of guessing on your end, but even if you're wrong, you should have plenty of space to still make contact with the ball.
Shift instead of sliding
The final tip from Zane is to shift instead of slide. In this technique, you keep your feet in the same position but shift your weight to the opposite side of your forehand.
This can be helpful if you don't want to commit to sliding completely or if your reaction just isn't fast enough to move your entire body. To work on shifting, practice hands battles while keeping your feet glued to the floor and focusing only on turning your hips and shifting your weight.
One thing to focus when shifting is not allowing your paddle to get too far behind your body. Many players make the mistake of putting too big of a swing on the ball, because they bring their arm back past their field of vision.
Instead, allow the paddle to occupy the space you've created and then strike froward rather than pulling back and then forward.
You can see the entire video from Zane Navratil here: