Although he's pretty sure Alphys isn't being entirely honest--what anime-loving shut in wants to participate in social interaction?--Mettaton decides he's going to call her bluff.

"Well!! If that's really what you'd like to do, then we can just drop this all off to a shuttle service and have them send it off to your room! I'm happy to accompany you on your trip through the nightlife, though perhaps not for any food or drink~"

Obviously. He's a robot, he can't do that.

"Of course, I'm more than happy to chat with my dearest friend and be the responsible sober party!!"