Biggest Tosser

Alright listen up, you big dummy. Explain bear is here. So, this "joke" you got here? It's a classic "your mom" insult. Very original, you aren't. First part just calls your mom a "tosser," which is a British slang word for someone who is unpleasant or, more vulgarly, a masturbator. The joke then doubles down by saying this mythical person is the biggest one on the planet. Wow, groundbreaking. But wait, there's more stupidity! The second part, which is the punchline if you can call it that, implies that because your mom is supposedly doing *something* with the speaker (which is the actual vulgar implied meaning of the first line), the speaker doesn't have to relieve themselves alone anymore. And apparently, that saves them from getting a strained blood vessel or arthritis from... solo activities. Because apparently, your mom is a physical therapy alternative. It's just a really crude, unfunny insult leaning on sexual innuendo and baseless claims to try and get a rise out of you. Now go away, your brain is probably hurting from processing all that, isn't it?