Milk solids
Canned foods and drinks can contain the weirdest stuff. We’re not just talking about icky solids like the one in this picture, but have you pondered what ingredients actually go into the product? Probably not. Anyway, when the OP fished out a solid object from a can of Monster Energy, they just had to know what it was.
At first, people weren’t sure what they were looking at. One user guessed that it would be a nugget of milk solids that had become mixed with other ingredients in the drink to create this gross-looking thing. This probably didn’t stop the OP from finishing their can of Monster.