'Teen Mom' Star Jenelle Evans -- Arrested for Harassment

"Teen Mom 2" star Jenelle Evans was arrested in North Carolina Tuesday after allegedly making harassing phone calls and threatening an unidentified person.

The 20-year-old MTV reality star was booked into the Brunswick County Jail and later released after posting $1,000 bond.

She later tweeted, "I'm free as a biiirrrrddddd :D."

The arrest could mean serious trouble for Evans -- who's still on probation for beating the living crap out of another woman during a street fight last year.

9:15 AM PT: Janelle posted a long message to her Facebook account after getting out of jail, claiming the person who accused her of harassment is her old roommate ... who's out to settle the score in some ongoing feud -- though details are unclear.

Jenelle's lawyer tells TMZ, "The charges against Jenelle are completely absurd and retaliatory in nature."