NASCAR Driver Ross Chastain Hits McDonald's During Rain Delay, Staff Freaks Out!

Talk about fast food ... how about a NASCAR driver leaving the Daytona 500 in the middle of a race to go on a McDonald's run!?!

That's exactly what Ross Chastain did on Sunday when a rainstorm delayed The Great American Race for more than 5 hours ... right after the 15th lap!

It was clear the weather wasn't going to let up any time soon, so Chastain hopped out of his racing car -- and into his personal car -- so he could speed over to a nearby Mickey D's to grab some food for himself and his crew.

Oh, he was still wearing his green racing suit when he pulled up to the drive-thru ... and the woman working the window couldn't believe it!

"AAAAAHHHH you just came from the racetrack?!" the woman asked.

"Yeah, we're racing, whenever it stops raining!!" Chastain replied.

The staffer couldn't believe her eyes ... saying, "This is my first time meeting a race car driver!" She even called over her co-workers to take a look!

RC explained he drives the #42 McDonald's car ... so it was only right he hooked up his crew with a massive order -- 6 of "everything" for his team and a hot fudge sundae for himself!!

When the race finally resumed, Ross finished in 7th place.