I see some people are mad about translating 'toriaezu nama' to 'whatsontap', but it does actually make some sense here if you're not used to 80 chapters of it. As he showed in the TL notes, the natives say it in katakana. They're pronouncing it awkwardly and they have no idea what those words actually mean - it's rote spitting back an incomprehensible set of syllables.
Literally, 'toriaezu' means 'for now' or 'first of all', and 'nama' means raw meaning unfiltered but the Japanese just use it for 'draft' in this context even if it's filtered. So when you use this in an izakaya, you are saying 'to start with I will have whatever your main house beer on tap is'. Also implied is it's whatever the default size is, usually chuu nama, which is about a pint, but could be much larger some places. Which is close enough to whatsontap for people who have no idea and don't even know (I think? Been too long since reading this) that you only use it for the first drink. For later beers you'd just say 'nama wo kudasai' (draft please) or 'mo ippai' (another glass) or dozens of other possibilities.
So it may be grating at first encounter, but I think it works here? And I say that as someone who has had hundreds of beers in izakaya in Japan - I've been on a lot of after work drinking parties for Japanese partner companies, they are real!