Yes, Oostburg is a real place.

"Well, the good news is, if I come across a hydra, I will fight it for you. It's your fault. You're all like, 'Let's hang out in Oostburg,' and I'm all like, 'Hell no!'and you're all like, 'C'mon,' and I'm all, 'dammit.' I was not at all surprised to discover there's a hydra in Oostburg. Fortunately, I know all I have to do is cut off its head...well, damn."