bye-bye. here's jeanne. >> reporter: you've heard of long goodbyes. >> this is the long -- >> bye-bye. >> you know what? bye-bye. >> i said bye-bye without making a deal. >> reporter: but when he said it and then walked out on chuck and nancy -- >> i very calmly said if you're not going to give us strong borders, bye-bye. >> reporter: it made headlines, even in france. it's one thing for n'sync to sing it. ♪ baby bye bye bye >> reporter: or anne margaret to belt it out. ♪ bye bye bye >> reporter: but this is potus, not some "snl" skit. >> bye-bye. >> bye-bye. >> reporter: about a mean airline. >> bye-bye. i'm sorry, what? what part didn't you understand? the buh? or the bye? bye-bye. >> reporter: often trump's signature kissoff line is accompanied by a signature hand wave. >> and if they said no, i would have said bye-bye. >> reporter: whether it's about