that one brings back an old flashback.
I know this works as I did just this about 20 years ago for someone.
Snag a broomstick from the janitors closet, a roll of strapping tape from the shipping department. Cut a stub from the broom using the saw on a swiss army knife, wittle stub a bit with knive and smooth by sanding stub to a tight force fit using the sidewalk. (this is hard on your finngers and knuckels) Hammer stub into head tube side then in the rest of the down tube using a rock. Tightly wrap the whole mess with strapping tape.
Was suprised when she showed up the next day on the same bike.