Why do some people who object to evolution try to claim that the laws of thermodynamics prohibit evolution?

they're just parroting something they saw at the creation museum. they haven't a clue about thermodynamics.

and the 2nd law, as I recall (I should look this up), is the one where temperature and pressure of items eventually come into equilibrium.

Ok thermodynamics is an application of the law of entropy.

The Darwinian theory of evolution does not go against the second law of thermodynamics but it does go against the laws of entropy the way it applies to information. Because the claim is that information is getting more orderly.

Entropy is not decreasing when a crystal develops because that is not the meaning of order as it applies to entropy. Order in entropy has a totally different meaning.

Order in entropy means for example a machine, information, a difference in energy.

Patterns would not be considered 'order' in entropy. in fact anything that repeats has a very high entropy that means it has a low order in the laws of entropy (this is counter intuitive but its the fact). this includes snow flakes, crystals, checked boxes, stripes etc.

Common English language uses the word order to refer to both of these kinds of things but they are very different. in fact according to the laws of entropy a pattern is the opposite of order.

Since information IS considered order with regards to entropy the question does apply.

And the energy from the sun or from anywhere else has nothing to do with the creation of that information.

We do not live in a closed system. better evidence against evolution would come from fields including but not limited to, astronomy, geology, paleontology, biology, chemistry, or taxonomy. Physics...not so much

The laws of thermodynamics only apply in CLOSED systems. Our planet is not a closed system; it gets its energy from the Sun.

In other words, they just stoopid.

It's a very dishonest tactic but it's what we've come to expect from people who believe in silly myths and invisible gods.

They don't actually understand what they are asking, they are just trying out some fancy sounding words they read on a creationist web site.