From the guys over at humortrain.com: A grammar lesson for tattoo artists everywhere.
The Purdue OWL Online Writing Lab explains the problem:
“A” goes before words that begin with consonants.
- a cat
- a dog
- a purple onion
- a buffalo
- a big apple
“An” goes before words that begin with vowels:
- an apricot
- an egg
- an Indian
- an orbit
- an uprising
Exceptions
Use “an” before unsounded “h.”
And yes, God is awesome.