遇到蛇撑伞假装是许仙
[yù dào shé chēng săn jiă zhuāng shì xŭ xiān]
It originates from a classic Chinese love legend of Xu Xian, where meeting a snake reminds him (of) carrying an umbrella like Xu Xian did when he met his destined lover who was originally a snake spirit. A humorous, self-deprecating take on fate's irony or unexpected events.