Chunky flunky Teen Mom AMBER PORTWOOD rocks chain-gang fashion wear in tres chic Indiana courthouse.

Portly Amber finalized her lame ass plea deal which mandates she must finish the Madison County Drug Court program and after evaluation, she'll be transferred to a rehab facility.

The MTV Teen Prego train wreck has been cooling her faux Manolos behind bars since last December in connection with felony drug possession.

Last month, she cut a deal to avoid spending five years behind bars by pleading not guilty to one count of a possession of a controlled substance and one count of a probation violation. 

All this legalese stems from the somewhat infamous domestic violence case where she “slugged” fatty baby daddy Gary Shirley FOR Teen Mom cameras.

Then the portly miss missed a probie hearing and when cops found pills she was not prescribed — slammer time!

A source told RadarOnline.com that Portwood's family believes “she is going to do a lot better" because if she screws up, "she will be in jail for a while."