Make sure you read yesterdays post before reading more...
Ok. The hand described was a real hand that did happen to me about a week ago. I am going to analyze the hand quite indepth but in reality most of this analysis did not happen during the hand. Sometimes you just have to trust your own experience and judgement and of course your instincts on decisions such as this. The fact is that after I made my decision I was not sure if it was the correct decision so decided to analyze it and see if I could come up with a firm answer.
2nd UTG raiser, who raises 6* the BB with 8 people left to act behind him will generally have one of the following hands :- AA, KK, QQ, JJ or AK. I will cover other possibilites later in the analysis.
Now, the betting pattern that was initiated by the original raiser is consistent as far as the above hands are concerned with the following combos of hands only :-
1 combo of KK - K

K

.
3 combos of AA - A

A

, A

A

, A

A

.
6 combos of AK - A

K

, A

K

, A

K

, A

K

, A

K

, A

K

.
We are
losing versus all of these combos.
and...
3 combos of JJ - J

J

, J

J

, J

J

.
We are
winning versus these combos. (Note only 3 combos of JJ because only when he has the JH does it logically fit in to the above criteria, any other JJ combo would just be counted as a bluff)
So that is 10 losing combos vs 3 winning combos which is just above 3-1 (3.33-1).
The original raiser bet $380 into $380 which gives us exactly 2-1 on the call which is about 1.33 short of a break even call or :-
10 times I lose $380 = -$3800
3 times I win $760 = +$2280
Loss = -$1520
Avg Loss per hand = $1520/13 = -$117 loss per hand every time I make this call.
Ok, so we agree a fold is certainly in order if we limit him to the above precise scenario. Unfortunately we can't do this because we have absolutely no information on him so there has to be a chance however slim that he has other possible holdings and we certainly have to factor them in somehow. This is where it gets tricky.
Other possible combos :-
3 combos of AJ - A

J

, A

J

, A

J

. (Very inconsistent with betting but small possibility)
2 combos of KJ - K

J

, K

J

. (Highly unlikely possibility)
2 combos of KQ - K

Q

, K

Q

. (A more likely possibility from the flop and beyond but loses credibility based on pre flop action)
1 combo of JT - J

T

. (Very unlikely pre flop action)
So here is a further 5 combos we can beat and 3 further ones we lose to. This would take us to 13-8(1.62-1) which would technically turn this into a call. However, you cannot just weight these combos in the same way as the ones we talked about earlier as they are far more unlikely. At an estimate I would say these possibilities would take us down by only a tiny bit, maybe to 2.5-1 which would still keep it as a fold.
The final thing we have to take into account is the possibility that he is just bluffing and doing a crazy bet on the end. This is of course impossible to quantify but I think it might just be enough to take us down from 2.5-1 to around 2-1 or maybe slightly below which would give us a break even call or slightly profitable call on the river.
Some things to consider though :-
1. He raised 6*BB (Increases the odds that he has AA, KK, QQ, JJ and AK)
2. He raised 2nd UTG (As above)
3. He did a full pot sized bet on the river (This is slightly inconsistent with only the J

as surely he can see it is unlikely he will get called by worse. You would more commonly see a half pot bet or smaller on the river if he held only the J

.)
4. There is still another player to act behind me if I call. A small percentage of the time he will be slow playing one of the above monsters and raise me.
Based on the the final 4 points I think a call on the end turns into a slightly unprofitable call. If any of the final 4 had been different, 4*BB or middle position raise or a half pot bet on end or no opponent behind me then it would probably swing back towards a call.
So I think we have answered the question and got about as close to an accurate answer as possible.
Correct Answer = Fold or Call (I think fold in the precise scenario laid out above is the correct play with calling being nearly as correct, when I say they are close we are talking 51% to 49% or closer, it really doesn't matter much.)
Wrong Answer = Raise (Anyone who suggested raise is clearly wrong - sorry!)
You are now probably wondering what exactly happened when I played it =)
Here we go, I folded on the river, the other guy also folded. The initial raiser then flashed J

J

assuming he had the best hand =). And no this doesn't prove a call is clearly the right decision =)
I'm glad after playing over a million of hands of poker where I have seen the above situations thousands of times that my gut instinct leads me in the right direction. I knew at the time that it was a very close decision between folding and calling and after all this analysis it is pleasing to get the exact same answer!