Unfortunately in this day and age things like this are necessary. I've been in situations before where I wish I knew how to ask for help. Luckily nothing seriously bad has ever happened, but I've felt threatened by pushy guys at a bar and had I known this trick, I could've had some back-up telling the guy to back off.
If you're ever feeling threatened or unsafe in a bar or restaurant you can ask for an 'angel shot.' This will signal to the bartender and staff to keep an eye out.
This term has been around for a while, so if there's a chance that the threatening person knows the term angel shot, you can ask "is Angela working?" This gets the same point across. That you're feeling unsafe and would like the staff to watch out and intervene if necessary.
A bartender on Tik Tok has gone viral talking about these and a lot of other safety tips so you can have fun and know of any potential problems that might arise while you're out enjoying yourself. Check out this and more of his videos on Tik Tok.