A stereotype of a lesbian that uses a trailer with all of her belongings in it to move with when she has found her next thing (girlfriend/relationship/situation). U-Haul lesbians are quick to jump into relationships in an unhealthy manner. This usually ends very badly.
"Alice brought a Uhaul with her with all of her things in it so she could move in with Jennifer. They just met. She is such a U-Haul lesbian."