What does "camp out" mean?

Sleep outdoors; also, stay somewhere for an unusually long time. For example, “We camped out in a field this night” (George Washington, Journal, March 18, 1748). In the early 1900s, the expression was extended to figurative uses, meaning simply “to stay somewhere for an unusually long time,” as in She camped out at the stage door, hoping for an autograph.