I have a thing where when I wake up I'm starving and need greasy or junk food ASAP, but if I don't get it within the first hour or so after waking up then I'll get extremely ill and throw it all up. I'm not sure what the science behind it is but my sister is the same as you where she can't have any food at all.
Yeah in my 20s I’d usually get GI issues when I had a hangover… but also in my 20s it would take a lot more booze for me to wake up with a hangover haha
Now in my 40s, I almost never drink that much in one night. So my lack of GI issues is probably just from less booze overall. And I’m more careful now about eating first and hydrating after booze