Verb - The act of completely ruining a sexual situation.
Noun - (1) The act of completely ruining a sexual situation, i.e. the act of "Marshalling." (2) A person who completely ruins a sexual situation, i.e. one who pulls a "Marshall." Whatever you do, don't invite this person to an orgy as they will instantly remove any sexual energy from the group instantly causing pussies to dry up and dicks to shrink nearly to the point of being inverted.
Dude, we were about to have an orgy with all our friends until that fuck totally pulled a Marshall by getting all pissy when his bitch started sucking on two dicks at once. I was like, seriously dude, lighten up, she was totally enjoying it!
A perfect person. Someone sweet and loving. You just melt in her eyes and you know you'll be safe. She has a voice of an angel and gives only the best hugs. Marshall is a big theatre geek, but does her best at what she loves. Deep conversations don't bother her. She enjoys cuddle dates and dancing in the rain. If you meet her, keep her in your life.