Finished up the framing on my coop last night and was curious as to the actual meaning of POP door. I though it might be an abbreviation, but it was not listed on the abbreviations thread. Did extensive search in this forum and found one thread where the question was asked, but no answer was given. Also googled it and found no mention of the meaning or the origin of the word, other than it referring to a chicken door. Was just curious as to why everybody on the forum uses the term when referring to the chicken door. Why not just call it a chicken door?