It means

1. In disorderly haste; confusedly; pell-mell. 2. Haphazardly.

ADJECTIVE: 1. Carelessly hurried and confused. 2. Haphazard.

NOUN: Turmoil; confusion.

ETYMOLOGY: Origin unknown.

Wikipedia points out that a helter skelter is an amusement park ride with a slide built in a spiral around a high tower. Users climb the tower and slide down usually on a mat. It is the precursor to the water slide. The term is primarily (but not exclusively) found in British English.

Dictionary.com defines as below, but does show an origin for it.

–adverb 1. in headlong and disorderly haste: The children ran helter-skelter all over the house.

2. in a haphazard manner; without regard for order: Clothes were scattered helter-skelter about the room.

–adjective 3. carelessly hurried; confused: They ran in a mad, helter-skelter fashion for the exits.

4. disorderly; haphazard: Books and papers were scattered on the desk in a helter-skelter manner.

–noun 5. tumultuous disorder; confusion.

[Origin: 1585–95; rhyming compound, perh. based on *skelt, ME skelten to hasten (< ?); redupl. with initial h parallel to hubble-bubble, higgledy-piggledy, etc.] Not sure who is right about the origin. Isn't English great. Even the experts can't agree on a lot of it.