Occasionally you can reverse the words without twisting the meaning and this probably is one of them. The tattoo artist probably copied this phrase from some song lyrics that reversed the words so it rhymes or goes better. BTW, you site is fun. Good job.
Mark: No, this really isn't one of those incidences... the phrase doesn't make sense with those words reversed.
Seriously Mark, get with it.
In British slang, "yob" means "hooligan" - it comes from reversing "boy", so it's literally "backwards boy"