哈哈 (hāhā) is an onomatopoeia representing laughter. It is widely used in both spoken and written Chinese, especially in casual conversation and online communication, to express amusement or joy.
哈哈,你说的这个笑话太好笑了。
hāhā, nǐ shuō de zhège xiàohua tài hǎoxiào le.
Haha, the joke you told is so funny!
她看到那张照片忍不住哈哈大笑。
tā kàndào nà zhāng zhàopiàn rěnbuzhù hāhā dà xiào.
She couldn't help but burst out laughing when she saw that photo.
哈哈,没想到你也会犯这种错误。
hāhā, méi xiǎngdào nǐ yě huì fàn zhè zhǒng cuòwù.
Haha, I didn't expect you to make this kind of mistake too.