Nine months before A Sad came to be on February 18, 2014 the Things were already exploring having "a sad" and how to provide comfort. With the right person and the right vibe, a bit of booping comfort can be quite nice.
And here's some more. I like head boops.
Transcript
Thing 1: I have a sad
Thing 2: Can I help?
Thing 1 just stares into space, looking sad.
Thing 2 boops their head onto Thing 1's chest.
SFX: Boop!
Thing 1 looks up and smiles a little. Thing 2 keeps their head in place.