Rascal Flatts' J.D. Rooney My DUI Bust ... Oh Deer, Lemme Explain!!!

Joe Don Rooney -- lead guitarist for the country music trio Rascal Flatts -- allegedly told cops a wild story about what led to his DUI bust. Literally, wild.

According to a police affidavit, obtained by TMZ, cops say Rooney told them he was driving his BMW in Williamson County, TN back in September at around 4 AM when a deer ran out in front of him.

Cops say Rooney blamed the deer for causing him to veer off-road and crash into some trees, which deployed his airbags. Cops say Rooney smelled like booze ... and that he told them he played golf earlier before going to a friend's house for drinks. The officer says he admitted to "one more than I should have."

What's more ... cops say Rooney bombed several field sobriety tests. As we reported ... he was ultimately arrested and taken to county jail where he was booked on a misdemeanor DUI charge. He was later released after posting $2,500 bond.

Rooney -- a founding member of the group -- is due back in court next month.

Rascal Flatts Guitarist J.D. Rooney Busted for DUI

Joe Don Rooney -- lead guitarist for the country music trio Rascal Flatts -- has been charged with driving under the influence after crashing his car near Nashville ... this according to law enforcement.

Cops say the musician was arrested after he crashed into a tree around 4 AM Thursday in Williamson County.

Luckily for Joe, he wasn't injured ... however, we're told he was taken to the county jail where he was booked on a DUI charge and released after posting $2,500 bond.

Along with playing guitar for Rascal Flatts, Rooney -- a founding member of the group -- sings the high-octave backup harmonies ... and plays the mandolin and banjo as well.

So far, he has not commented about his arrest or car accident.

Casey Anthony's Parents Reach Out to Rascal Flatts

Casey Anthony's parents are trying to arrange a meet-and-greet with the band Rascal Flatts -- all to give the lead singer one big thank you for writing an emotional tribute to Caylee Anthony.

TMZ has learned ... George and Cindy Anthony reached out to the band's reps this week after hearing the song, "She's Going Places" -- which lead singer Gary LeVox (right) co-wrote with another singer named Cledus T. Judd.

But the band isn't exactly in a hurry to respond -- a rep for Rascal Flatts tells us the band is mulling it over and has yet to decide if they'll meet up with the Anthonys.

If you haven't heard the song, the lyrics are pretty heartrending -- "She was just a baby, barely 2 years old / A story that shouldn’t have to be told" -- so if you're in the mood to tear up, take a listen.