Q: What is the best way to talk to a giant?
A: Use big words!

Explanation: When I think of giants, I think of characters like those from Roald Dahl’s The BFG, Jack and the Beanstalk, and A Monster Calls.  They are larger than life beings that can be good or evil, or a bit of both. Giants, though, are generally considered to be the antagonists in a story, the bad guys.

As for the idea of big words, well, sometimes children are told to use words to explain how they are feeling.  Also, at times adults suggest that children use big words to explain an idea with more detail, this could be to talk about feelings or to explain something when they are writing. (That reminds me of a 1st grade student who once told me that his head hurt, that he had a headache.  When I asked him to point to the part that hurt, he pointed to his loose tooth. Yes, a tooth is in your head but we understand toothache better in that situation.)

Big words could also refer to the size of the words.  You usually see big words on a street sign or a billboard, whereas you typically see smaller words in a book or in the small print of a contract.

This joke is funny because it plays with the idea of big words meaning more detailed, or just using large sized words, large like a giant.

Here is They Might Be Giants singing Boss of Me-