This bug has been in the game since start of this year when I bought the game. When you kill a chicken and pick it up, your character looks like they're holding the chicken even if you get rid of it. So whole holding a gun from your perspective, others see chicken.
This bug was found on Playstation 4 Pro.
This is how I've always done when it happens:
Kill chicken with a melee weapon.
Hold the chicken in your hands.
Do throwing stance (double tap square).
Cancel or throw the chicken.
Now your character should be bugged.
Not 100% if it happens the first time, because sometimes I like to throw the chicken around when I'm bored.
Relog fixes it, but you wouldn't know unless someone tells you. This bug is minor, because if you meet a player, they might think you're harmless, because they see that you're just holding a chicken. But you actually have a loaded gun.