Chief Keef -- Arrested for DUI After Rehab

Chief Keef really does hate being sober -- TMZ has learned, the rapper was popped for DUI ... less than two weeks after he left rehab for weed.

Law enforcement sources tell TMZ, Keef was pulled over in Highland Park, IL early in the AM on March 5th for having expired tags on his 2010 Jeep Cherokee. When officers approached the vehicle, we're told it reeked of pot and, according to our sources, Keef openly admitted to smoking before driving.

We're told police administered a field sobriety test and Keef choked. He was placed under arrest at the scene. In addition to DUI, Keef was also charged with driving on a suspended license and cited for having no proof of insurance.

The rapper was subsequently released after posting $300 bail.

It's crazy for several reasons -- Keef had just left court-ordered rehab for weed addiction in February ... and three days after his arrest, he posted a pic of himself smoking weed on Instagram.