When St. Patrick was banishing snakes from Ireland, one snake didn’t want to leave (and GO fans can guess snake’s name). Then St. Patrick built a wooden crate and assured the snake that it can never possibly fit inside the crate. The insulted snake was bent on proving him wrong and got trapped. And St. Patrick swiftly sealed the crate and threw it into the deep sea waters.
Crowley was drifting for a while and was fearing a soon discorporation, but he was finally washed ashore. And at the very same time Aziraphale was sitting on the said shore, pondering on eternal matters. Noticing the crate, he decided to open it out of curiosity. As soon as he opened it, rejoiced Crowley jumped right into his arms, changing his shape on the fly.