This is the Paris Gun, a German WWI long-range (130 km), large-caliber (21 cm, later 24 cm) artillery piece intended to shell Paris. It seems to have been woefully inaccurate and ineffective at anything but intimidation. The "Campari" connection is a bad pun: "M" and "N" are sometimes interchangeable in Japanese, and in French the "S" in "Paris" is not spoken. "Gun Pari" => "Canpari".

http://en.wikipedia.org/wiki/Paris_Gun
http://en.wikipedia.org/wiki/Campari

So one could say that the Paris Gun, was a weapon about as reliable as a drunk loli :o