The term "Fat Lizard" originated in 2022 in South Carolina, USA. It is best described as:
Snakes are sneaky and remain very low-key when moving through the grass. A Fat Lizard may try to mimic the movements and behaviors of a snake to try and be sneaky, but they fail to do so.. Don't tell them that, as they are under the impression that they are indeed being sneaky.
With that background information, we arrive at the term "Fat Lizard" to describe a person who acts like a snake but is very obvious and not effective at being sneaky. You will see these people and their intentions from a mile away, but they still feel the urge to try and be sneaky, even if they aren't good at it.
"Look at him trying to tell the boss on us and then come back acting like friends. Talk about a fat lizard.."