Taylor Swift -- Hooks Up Pro Snowboarder Greg Bretz ... It's Your Lucky Day, Dude!!

Taylor Swift just gave a pro snowboarder a heart attack we're guessing ... 'cause all Greg Bretz wanted for his birthday was for Taylor to show him some love -- and it just happened.

T Swizzle recorded a shout out to Greg -- posted by a mutual friend of theirs -- telling him, "Happy birthday, Greg. Amazing!"

Bretz turned 24 Friday -- and earlier this week he was crushing hard on Taylor. First, he posted videos of himself doing snowmobile tricks ... using "Blank Space" as the soundtrack.

He even came on TMZ Hollywood Sports to talk about how Taylor inspires him when he's on the mountain.

In the video, Taylor mentions something about Greg scoring -- could be a sports reference, or y'know ... ;)