To masturbate, to knock one off.
> eg: One
> 'Man, i could do with a [Josh], i'm so horny'
> 'Well, [to Josh] now would be nice, but you'll have to wait'
> Or
> eg: Two
> Joe: 'Ahh, that [Josh] last night was mega'
> Conor: 'I could really use one, I haven't had a [Josh] for quite some time.'
> eg: Three
> 'Look at her! I'd give that a [Josh]!'