President Barack Obama -- Golf with Alleged Prostitution Solicitor

President Barack Obama wrapped up his Hawaii vacation on Christmas Eve with one last round of golf with close friends ... including an old school buddy who was arrested on suspicion of soliciting a prostitute.

It was Barack's second round of golf in Hawaii in the last week with Bobby Titcomb, who was popped in April 2011 after allegedly approaching an undercover police officer for sex in downtown Hawaii.

Titcomb pled "no contest" to the charges and was fined $500. Since Titcomb stayed out of trouble for six months after the plea ... the charge disappeared from his record.