OLLIE LESSONS, BABY!!!

Addison Rae -- one of the most-watched TikTokkers on the planet -- got a surprise meeting with Tony Hawk at The Berrics skatepark in L.A. this week ... and the two got to skating immediately!

20-year-old Rae explained to 52-year-old Hawk she's just getting into the sport ... and Tony LOVED it -- and offered her a million tips on how to ride like him.

No, there were no 900s ... but Tony helped her with some ramps -- and even gave her ollieing tips!!!

The clip is pretty cool, you can tell Addison is passionate about riding ... and Tony couldn't have been happier to see that.

"I think it's really cool that you're introducing skateboarding to a new generation of especially girls," Hawk said. "Because it is the great equalizer and it's all-inclusive and I feel like if kids can just see how fun it is and what it can do for them, they'll want to do it."

"And, I feel like you're really promoting that well. It's really cool."

FYI -- Addison truly is introducing the sport to A LOT of people ... she has over 68 MILLION followers on TikTok!!!