Rubbing the penis till sperm comes out.(only men do it):D
of courseANyone can.
girls masturbate mostly she use her fingers some girls try their TV remote and some try back of knife some girls use tooth brush, Mobile's, mic, rubber pipe, tools which is 5inc or more longer to put...
Same way then in any another room. Except if you are a girl, you can use the shower head to stimulate your clitoris.