Similar to skiing
but instead of jerking off two penises it is when a man jerks off himself while performing a reacharound on another man.
When asked if skiing or giving a sidecar was a more homosexual act, Jerry was perplexed. On one hand, skiing has twice as many foreign dicks in your hands but on the other hand with a sidecar he would also be hard therefore presumably enjoying himself. Jerry reasoned that one could reluctantly ski but a sidecar implies self pleasure.