Brothers -- What They Do When They Don't Know I'm Watching

Too cute to choose just one, so I'm giving you three!

Hewitt : "My brother is so nice to read me this story."
Harrison : "Are you listening, Hew? This is some funny "gunk" (Harrison for "junk")."

Hewitt : "Okay, now he's really into this book. This might be my chance..."
Harrison : Has forgotten that Hewitt is there.

Hewitt : "I can't wait another second -- I have got to MOVE on those slippers! Must touch the fuzzy bear..."
Harrison : Completely unaware.