The meatus (full name urinary meatus or external urethral orifice) is the opening of the urethra where urine and/or semen exits.
In males the meatus is found on the dick head. It's a little vertical slit and often looks like a tiny little pair of labia majora (fanny flaps). The flexibility of the male meatus is responsible for mens ability to have varying pee streams.
Females have their meatus a couple of centimetres behind the clitoris right in front of the vagina hole. Lady meatuses don't look like labia (we already have two sets of labia so we're fine), they look like a little hole with a very slightly raised circumference.
Thumbnail image via Flickr