Fun asides to leave in your thesis/dissertation:

Passive aggressive thank yous 

Inside joke acknowledgements

Jokes in footnotes

Unacknowledged puns

Saucy comments like “as much as researchers would like this to be the case..”

Random trivia in footnotes

Unnecessary appendices (songs listened to while writing, lists of weird historical events, etc)

Citations of yourself, because goals

Unnecessary citations of your academic friends 

Song lyric quotes in italics as chapter openings

What else you got? Looking to spice this document up.