Something that's rollicking is really fun and playful. When you throw a party, you hope your friends will describe it as rollicking.
Parties with live music and great food are usually rollicking, and a wonderful game of charades with your family can also be rollicking. You might even describe a funny movie or a song you can dance to this way. The root of rollicking is a nineteenth century verb that we don't use much these days, rollick, "to behave exuberantly." It, in turn, is most likely a combination of frolic and roll.