1) An advertising campaign/gimmick by the Pot Noodle company about people who blow huge horns when they want pot noodle.
2) Now synonymous in England with having a boner/stiffy/erection or being amorous or horny in any way.
Advert: "Do you have the Pot Noodle Horn?"
Veiwer: "lol, wut?"
Bob: "Man that girl was so hot, I had the pot noodle horn!"