Okay, I’m drawing a complete blank. What are the words to the capybara song?
Capybara sitting in an old [something] tree…
I thought it was the Kookaburra.
Kookaburra sits in the old gum tree,
Merry merry king of the woods is he…
Why would a Mexican four-pocketed shirt sit in a tree? 
Aha! You are correct.
It’s been so long since I was a kid… 
It’s kookaburra, not capybara. A kookaburra is an Australian bird. A capybara is a hundred-pound rodent from South America. If you spot one of those sitting in a gum tree . . . move out of the way!
b/c it was being worn by a giant rodent, it would seem. :o