Jon raises a brow at that. Clearly he is too curious for his own good not to try that at least once.

His expression turns thoughtful, then. "I admit I- Never quite got the hang on... Pet names. Or just having nicknames for other people. Then again, my own experiences with them were never really on the positive side. Bullies had their dismissive nicknames for me for the most part, and when Tony started calling me Boss out of the blue when we met in person for the first time... Well. Let's just say I have had some unpleasant memories of someone else using that name on me in a friendly manner. It... Rubbed me the wrong way."