The key test is whether Rowan Atkinson would induce laughter saying the word while playing his Schoolmaster character: [video=youtube;FiWJWLCoH2M]http://www.youtube.com/watch?v=FiWJWLCoH2M[/video] Plectrum, orifice and carbuncle all excellent shouts from that video.
llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch Apparently the forum won't accept that there is indeed a word that is this long, and puts an auto-space near the end.