Britney Spears -- Watch The Paint!! Still A Louisiana Hood Princess

Britney Spears proved you can never truly get the country out of the girl ... by using the hood of her $150k Mercedes as a front row seat.

Brit and Lynne Spears were in full soccer mom and grandma mode in Calabasas this weekend cheering on Brit's son from the hood of her ritzy G-Class ... so they're probably gonna want to get that hood buffed out.

That's straight up Friday Night Lights stuff ... but if she's truly legit, she better have a keg and a grill going on in the back.

Cue banjo music.