Am I crazy or is this "strange" play?

[jackdaniels]

PokerStars 3/6 Hold'em (9 handed) converter (http://www.selachian.com/tools/bisonconverter/hhconverter.cgi)

Preflop: Hero is MP2 with Q/images/graemlins/diamond.gif, J/images/graemlins/diamond.gif.
<font color="#666666">2 folds</font>, MP1 calls, Hero calls, <font color="#666666">3 folds</font>, SB completes, BB checks.

Flop: (4 SB) 2/images/graemlins/club.gif, K/images/graemlins/club.gif, K/images/graemlins/diamond.gif <font color="#0000FF">(4 players)</font>
SB checks, BB checks, <font color="#CC3333">MP1 bets</font>, Hero folds, SB calls, BB folds.

Turn: (3 BB) K/images/graemlins/heart.gif <font color="#0000FF">(2 players)</font>
SB checks, MP1 checks.

River: (3 BB) 4/images/graemlins/spade.gif <font color="#0000FF">(2 players)</font>
SB checks, MP1 checks.

Final Pot: 3 BB

Results in white below: <font color="#FFFFFF">
MP1 has Jc Ks (four of a kind, kings).
SB has Ac 5c (three of a kind, kings).
Outcome: MP1 wins 3 BB. </font>

[Nick C]

Wow.

Yeah, checking behind on the river with the nuts is pretty bad poker.

I have no idea what MP1 was doing in this hand. Maybe he thought he only had trips or something and was worried about being outkicked. Maybe he lost track of the streets and didn't realize that the only thing that would come after his second check behind was showdown.

It is puzzling. I guess what's most likely is that he misread his hand, somehow.