Cody's character in House of Cards
You call Duncan your 'little donut' as a reminder of accidentally spilling your Dunkin coffee on him and calling him the donut when you met, he thinks it's adorable and loves it because it's an inside joke no one else knows (and likes when you bring him donuts and cheap coffee which he oddly enjoys)
Bonus:
Everyone else around him is too hoity toity to have ever heard of Dunkin coffee and keeps wondering why the fuck you call him donut. Is it sexual? Do either of you have some kind of donut fetish?