Bizarre river shoving from loose-passive player

[Wolverine]

I was playing NL100 and got into a number of pots with a loose-passive player. He kept making this bizarre move of showing no aggression in the pot and then shoving huge on the river, and he always seemed to be doing it against me. This was annoying because each time I would have a marginal hand like top pair with a mediocre kicker, or second pair or whatever.

Anyway we get into the following hand after he has pulled this move like 3 times in less than half-hour:

Full Tilt Poker - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 6 Players - (LegoPoker HH Converter)

SB: $332.90
BB: $102.50
UTG: $98.50
MP: $64.70
<font color="black">Hero (CO): $146.75</font>
BTN: $317.45

<font color="black">Preflop:</font> Hero is dealt Q[img]/images/graemlins/club.gif[/img] K[img]/images/graemlins/club.gif[/img] (6 Players)
2 folds, <font color="red">Hero raises to $3.50</font>, BTN folds, SB calls $3.00, BB folds

<font color="black">Flop:</font> ($8) 3[img]/images/graemlins/heart.gif[/img] A[img]/images/graemlins/diamond.gif[/img] Q[img]/images/graemlins/heart.gif[/img] (2 Players)
SB checks, <font color="red">Hero bets $5.00</font>, SB calls $5.00

<font color="black">Turn:</font> ($18) 4[img]/images/graemlins/spade.gif[/img] (2 Players)
SB checks, Hero checks

<font color="black">River:</font> ($18) K[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">SB bets all-in for $324.40</font>, Hero ???

[Wolverine]

BTW I'm not necessarily asking how to play the hand, more trying to understand this opponent.

[EddieRooo]

Fold he has Axs

[Wolverine]

Also the other pots he did this were on very dry boards. He'd call down my raises and then shove huge on the river. There was no clear hand he could have had so I had to keep giving him credit for a set, TPTK, or two pair off of any of the wide range of starting hands he could have had being loose.

[Rainclouds]

This is just the nut flush.

It is possible that he had the nuts 3 times within half an hour. And every extra time he shoves, the chance gets bigger that he gets called so he will keep overshoving the nuts.

[Wolverine]

Yeah I guess it's pretty obvious. Basically I put him on Ax, but I was paying too much attention to his shoving that I missed that the K on the river made a flush possible (inexcusably bad of me). All I saw was that I made two pair and he made another of these ridiculous shoves. I felt he was out of line and there was a decent chance my two pair was good. So I call, like a right dick, and he has 4h7h or something and I get stacked. Awful play from me. I guess I just wanted some reassurance that he was probably doing this with the nuts every other time. When I think about it, on a previous hand he shoved and, while I was thinking, said 'call' in the chat, which always sets alarm bells off that he does in fact want to be called so I folded that one easy. It's just this time... bah. Awful play. [img]/images/graemlins/frown.gif[/img]

[FastPlaySlow]

passive + river shove overbet = nuts

[Kilillan]

yeah calling this is beyond terrible.