Overbet donk on coord board. I have middle overpr.

BB has a bizzarre, unpredictable style. Up to this point, the only hand of note was a pocket pair of 9s that he went all the way with despite 2 overs on flop and 1 on river.

At this point I'm a relative newcomer to the table.

What to do with the donk overbet? If I raise it I'm playing for stacks (and I have no draw). If I call it I'm probably playing for stacks.... it seems like calling is the worst thing to do here. so what would you do?

PokerStars No-Limit Hold'em, $1.00 BB (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver Cards)

MP1 ($98.50)
MP2 ($98.50)
MP3 ($96)
CO ($65.50)
Button ($15)
SB ($93.40)
BB ($129.85)
UTG ($48.75)
Hero ($99)

Preflop: Hero is UTG+1 with http://www.flopturnriver.com/phpBB2/.../smiles/jc.gif, http://www.flopturnriver.com/phpBB2/.../smiles/js.gif.
UTG calls $1, Hero raises to $4, 5 folds, SB calls $3.50, BB calls $3, UTG calls $3.

Flop: ($16) http://www.flopturnriver.com/phpBB2/.../smiles/7h.gif, http://www.flopturnriver.com/phpBB2/.../smiles/8h.gif, http://www.flopturnriver.com/phpBB2/.../smiles/6s.gif (4 players)
SB checks, BB bets $26, UTG folds, Hero says WTF and ....????