Indonesian slang for someone who tells a joke so unfunny you can't help laughing.
Sergio thinks we're laughing because he's hilarious, not because he's a jayus.
Jayus is an Indonesian word (that I just made an English word) that conveys the awkward humor behind a joke delivered so badly that you can’t help but laugh. In English, we sarcastically say, “That’s so funny I forgot to laugh.”
When a joke is delivered in a horrible manner, you say, "That was fuckin' jayus bro."