I'm very confused, too.
So, what's going on here?
This is what I get from the story:
1. YAX's friend is the manager and he's joking around with YAX,
2. YAX's out with another woman and OAZ actually calls and so, his friend or the manager of the restaurant, indeed tells him so seriously, and
3. OAZ is indeed in the restaurant but in the restroom and another woman calls for her man but the manager mistakes YAX to be the calling woman's husband.
So, which is it, YAX?