I'm not kidding you. It does work.

我不是戏弄你，那的确有效。

《牛津词典》

I'm not kidding, Frank. There's a cow out there, just standing around.

我不是在开玩笑，弗兰克。那边有一头奶牛，就在那里站着呢。

《柯林斯英汉双解大词典》

I'm not kidding, I'm serious.

我没开玩笑，我是认真的。

youdao

No, I'm kidding but I mean I'm not really kidding, but I'm kind of kidding.

BBC: Golden Globes: In quotes

This is known in design parlance as "dead-cat space" I'm not kidding and designers try very hard to minimize it.

WSJ: 2013 Subaru BRZ Review: It's Thinker Than You Fast It Is | Rumble Seat by Dan Neil

That boy was the first ever worm charming world champion - say that three times fast - an Englishman named Tom Shufflebotham - I'm not kidding.

NPR: The Tricks And Tools Of Worm Charmers