What is Gentlemans Wash?
1.
the washing of the male member in the sink usually in the toilets of a pub/club before the act of sex with a one night stand or a 10 pint princess
i've just pulled best go freshen up and have a quick gentlemans wash in the bog
See
2.
washing of the male genitalia in the sink
Tim didnt have time for a shower, so he got his fella out for a "gentlemans wash!
See