I believe that spike shouldn't have left Bubbu alone in such a dangerous place. Bubba was scared and even asked if he could spike would run he was vulnerable and not ready to be alone . I think Bubba's pants flying away was no accident, I think it was planed. Spike leaving is a bit convenient, I mean life has a way of working its self out. Spike going just when Bubba sees a shadow at the top of the Water Tower. But there is a chance of it just being bad luck. I also think it was lucky for Spike, because they both could of been kidnapped or killed.