Personal jokes that seem perfectly hilarious in the indulgent hush of one's own bedroom sometimes (often) fall flat (splat) the moment an actual audience (mom) is introduced.

当你在自己的平淡无奇的房间里肆无忌惮的释放自己时，恰好你妈妈进来了，你自己出洋相似乎就是个笑话。

youdao

If, as Mr Magueijo claims, he wanted us to take the diatribes that litter his book as jokes, they fall crashingly flat.

ECONOMIST: Modern physics