Game is 1/2. Hero is UTG+2
Hero - 1700. MP1 - 1100. SB - 560. All others involved in the hand ~200-400.

SB was relatively new to the table, approximately an hour. Could view Hero as LAG at this point. Mid 50s - early 60s gentleman. Not quite OMC image.

MP1 had been sitting next to Hero for a few hours. Certainly viewed Hero as LAG. Late 40s - mid 50s.

The game had been playing fairly loose and packed with action for a few hours. Recently, the table had calmed down slightly and was playing a little more standard. Mainly due to one of the perpetrators having lost most of his stack. Hero likely had a split image amongst the table. Newer players relatively unsure and the mainstays see Hero as LAG.

Action folds to Hero. Hero opens to 10 (6d6c). (standard opening size for Hero with no limpers). MP1 calls. HJ and CO call. SB raises to 45. Hero, MP1, HJ and CO call. 5 ways to the flop. (227) Flop 457r. SB thinks for a few seconds and open jams.

What does Hero do and why?

SB is offering a price so close to break even that I need a an equity calculator and scratch paper to tell if it +ev or not. I am definitely ranging him to TT+. Since we hold two 6's it is unlikely anyone else has one. I like flatting here. MP1 would be the only player who could call a part of our raise and our draw is big enough that I think it is +ev to let the other two players come along. If, somehow, the SB made this play with AK then we are +ev even if every else folds too.

Its probably an overpair (TT+)
I think calling here is more on the gambling side...
525 + 525 + 227 = 1275
525 / 1275 = 1 / 2.5 = 40%
So you need to win 40% of the time if other players fold.
You have 2 + 8 = 10 outs so about 40%.
I dont think I like to gamble 250bb for a EV neutral spot...

I just fold... I mean its not bad to call mathematically speaking... But I think you can have better spots. Depends on your roll and tolerance to variance too.

Its definately a weird/interesting spot since sets are like VERY in the calling ranges of MP1, HJ and CO. And probably their only calling range after you call I think they fold over pair...
Against a set, you now have 8 outs but have to dodge board pairing so maybe about 28-30%? But now your equity is a bit harder to calculate since there would be a side pot/bigger pot depending on who got the set.

Fold. The call is slightly -EV when SB has a big overpair, which is obviously what he has (you need 40% equity and have 38%). The possibility of someone calling behind us just makes things worse - if we range another caller at say { 77-44,86s,76s,65s } then our equity three ways decreases to 24%. So basically this thing is going to be -EV any way you slice it.

If closing the action, this is a marginal high variance call. Not closing the action, this is a fold.

you raised too small pre. If this is your standard open thats a leak. Make it $15 and it wnt go so many ways.

As others stated, this is basically a math decision, not hard to put SB on a range, although I think as far as the "marginal fold", SB derps with AK some small % here which is often enough to turn it into a marginal call if there werent players behind.

Not a chance that raising 5x as the first person into pot is a leak . I have just as many hands that 0-2 callers at 5x being the first person into the pot as I do with 3+ callers. If I was in CO and half the table limped and I made it 5x, that could be a leak. However, that was not the situation I faced.