The joke wasn't much of a surprise. If Malgus didn't have some sense of humor he would have killed Obi-Wan several times over.

He smirked faintly in response to it, but quickly got reduced and stopped from moving to collect a datapad by the rest. That was a surprise.

He blinked a few times and cocked an eyebrow up. "Is that an invitation or are you kidnapping me?" Was that a joke? Maybe. "Where are we going?"