Worst one hour of my week, and the week's just started...

What would you say to a Hongkongese who decides sit right behind you, talks loudly and burps non-stop for a whole hour?

This morning, as I boarded the bus from Taipei to YiLan, I was greatly annoyed by another passenger, the encounter was so... disgustingly engrossing that I was on the verge of puking multiple times during transit.

It was seven-thirty-five, I was anxiously waiting for the bus heading YiLan to arrive. My three-hour Chinese Language course starts at nine-ten, the transit time is usually a slight bit over one hour, so I have to catch the next bus to YiLan no matter what.
At seven-forty-five, the bus finally came. As I boarded the bus, I noticed a group of about five Hongkongese females trailing me to my seat. I didn't give them much thought. They were quite quiet for foreigners when waiting in line for the bus, I need some rest so I can be focused in classes today, perfect.
But, as the bus started rolling, my suffering started. A really loud and contiguous burping noise started behind me.
'Maybe she had too much for breakfast, at least she's not puking.' I thought.
However, the burping sound did not seem to cease, in fact, it's gradually getting louder over-time. I started to regret not bringing a headset from home today... It may be that her companion felt embarrassed, because she started to converse with the 'burping girl' (in Cantonese, of course). To be honest, her doing so only lead me to discover a even more disturbing 'talent' the 'burping girl' had: Now she's still burping, but she manages to converse with her friend during each short intervals of her burping. Her disregard for other passengers REALLY started to piss me off! To top that off, her decision to sit right behind me in a filled bus basically made me her most 'intimate' listener. I felt ill to the point that I was in the verge of puking my breakfast out several times.
I felt the urge to ask her to sit all the way to the back of the bus, if stop burping wasn't an option, but I didn't. Luckily, the lot of Hongkongese got off the bus at JiauXi, so I had time (20 minutes until arrival to YiLan) to recover from the extreme discomfort I felt since I sat down in my seat back in Taipei.
My impression of Cantonese-speakers from that point on... 'Not pleasant' is all I have to say.