Could hiccuping be bad? Why am I doing it so much?

Ice heard you hiccup cuz ur stressed but it's summer and I'm just chilling so I'm not. Today I've had six different hiccuping series-and counting. They can last from five min to bout ten. They usually dont hurt but sometimes they do. Water or any other trick doesn't seem to make them go away. Anyone know why happens? Could it be serious?