Actually, usually when I get hiccups, I can also feel and hear fluids and gasses sloshing around somewhere inside me, and part of me absolutely wishes I could burp during those times.
Keep in mind, they say the human intestines are something like 27 feet long, and are packed in there as mostly a random mess of a ‘knot’, so to speak. So just because you happen to have gasses somewhere in your belly doesn’t always mean the gas is immediately in a spot ready to go either way up or down.