There are some dances which make it easy to swap sides, "Montgomeries'
Rant", for one, by providing certain "moments".
Once, at the Fredericton Weekend, Connie Powell and I got on the floor to do
"Bonnie Stronshiray" and we both wanted to dance as man. So, we resolved it
by dancing a one-and-a-quarter turn instead of the three-quarter turn during
the half-reel-of-four progression at the beginning of the second repetition,
et voila! The looks of surprise on the faces of the dancers in the set were
priceless. Since we are both females, most weren't quite sure what had
happened and the dance flowed smoothly despite our gender-change. (Apologies
to those who are not familiar with the dance.)
I hasten to add that this is NOT recommended practice if you are not very
familiar with the dance, and it is not fair to inflict it on a set with a
large number of beginners in it. However, the situation described above was
during a dance marked "for experienced only", and no harm was done.