Rizz is short for "charisma," and it simply means to charm and woo a person. It's pronounced, well, rizz, just likes it's spelled. The term found it's way into teen slang through TikTok and other social media, like Twitch. Rizz is also another word for, "Pick up lines."
"DAMN! My boy got some rizz, sheeshh!!"
"I'ma go rizz shawty up!"
"Yo chat, you see that Humpty DUMPTY over there? I'ma go rizz it up."