How about either that Col. Klink-like monocle of Prof. Stokes in the middle of a crop circle or the good professor's Sicilian talisman (with the accompanying Italian incantation) which, incidentally, Barnabas never returned to Stokes? (You can't lend that man anything!)
Of course, a representation of a Harley-Davidson motorcycle would be the immortal Buzz Hackett's crop circle.
And, how about a "whoopee cushion" crop circle for the irrepressible Carl Collins?