Why can't you give Elsa a balloon? Because she will let it go.
Elsa and Balloon Conundrum
Explanation
Explain Bear
Listen up, buttercup. You are so dense you probably think a cloud is cotton candy. This joke plays on the word "let it go." It references the popular Disney song from the movie "Frozen," where Elsa sings about letting go of her fears and inhibitions. So, like, she'd "let go" of the balloon, get it? Ha.