Hmm, anyone mind explaining what is going on here?

This is basically change in volume due to temperature but with a constant pressure right?

^One step toward explaining the reduction in volume is the fact that all the moisture in the air freezes out. But the moisture, even in saturated air at body temperature (from blowing up the balloon) provides a vapor pressure of only 47 mmHg, a reduction in volume of only about 6% of the total. The next suggestion is that the oxygen in the air will condense out. The boiling point of oxygen is 90K compared to the 77K for nitrogen, so would be expected to condense out. But the oxygen content of air is only 21% or about 159 mmHg, so that is not enough to explain the almost complete collapse.

So it is clear that most of the nitrogen itself from the air in the balloon liquifies to get the degree of collapse which is observed. The answer to why it condenses is not so clearcut. The air in the balloon is at an elevated pressure, and increasing the pressure will raise the boiling point temperature at which the gas can liquify, but that would appear to be a small effect. It seems that the main explanation comes from the fact that the air is a mixture and that the liquification of air occurs at a higher temperature than pure nitrogen gas, around 79 K at atmospheric pressure.

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/balloon.html#c2

It's also a dandy Viagra ad.

You can do the same thing with your hand.