" To never live something down" means that people will never forget about something that was bad or embarrassing about you.

“永远不要让自己失望” 意味着人们永远不会忘记你的坏事或让你尴尬的事。

" To live (live) something down" means to have something embarrassing happen to you and then try to continue on with your normal life – when you hope other people have finally forgotten about this embarrassing moment that you have.

“生活（生活）一些事情” 意味着你遇到了一些令人尴尬的事情， 然后试图继续你的正常生活——当你希望其他人最终忘记你所经历的这个尴尬时刻时。