Why does Corporal Rios say he ordered a monkey from eBay in Chapter 9?

In Chapter 9, Corporal Victor Rios receives a large package in the mail and the soldiers gather around to see what's in it; Rios says he ordered a small monkey from eBay from Wyoming, but that it shouldn't be this big; he ordered the monkey because his aunt had given him a small one to wear around his neck as a kid for good luck.