Assuming this is a tourney. If not, it is always a fold. You only make this call if so short stacked that that 150 is a significant portion of your chips. Realize that this is really a bad hand you are playing ... I don't think I would make this call unless my stack was under about 250 after posting the SB. If that was the case, go all-in. If you have a bigger stack than that, remember that you will have 4 hands before being the big blind again, and you will probably get a better hand than K5o in 4 hands.