Following Chinese trends, Simon begins to use WeChat (微信 wēi xìn: literally: "micro message"), a mobile text and voice messaging communication service popular in China. What he usually does is click the thumb icon to show praise or approval, just like that on Facebook. He has been taught it is said, "点赞"(diǎn zàn).
bài tuō bāng wǒ diǎn gè zàn ba jí mǎn 50gè ，wǒ jiù kě yǐ lǐng miǎn fèi lǐ pǐn lā
Please click the "like" button for me. If I get 50 likes, I'll get a free gift!
xíng wǒ zhè jiù diǎn
Alright, I'll do it right now.
nǐ hé lì lì shì hǎo péng yǒu ma
Are you and Lili good friends?
suàn bú shàng yě jiù shì diǎn zàn zhī jiāo bà le
Xiao Lin: 算不上，也就是点赞之交罢了。
Not really, we are only casual acquaintances.
"点赞" (diǎn zàn ) is internet slang. "点" means "to click," and "赞" (zàn), literally meaning "praise”, is a button in the shape of a thumb in some social networking apps, like WeChat, so if you like a message or a link or something your friend shares, you can click the thumb sign.
In the dialogue, Lili asks Xiao Lin to “点赞” so as to collect enough "likes" to get a free gift. Simon asks if Xiao Lin and Lili are good friends, but Xiao Lin says their relationship is only “点赞之交”(diǎn zàn zhī jiāo), which is a buzzword newly composed for the internet. It refers to a friendship that is not sincere or deep, but rather the interaction between the two people is merely clicking a button.
"交" here means "friendship". “之” is a structural auxiliary word. In Chinese, there are many phrases to describe different kinds of friendships, for example:
[wàng nián zhī jiāo] 忘年之交: friendship between generations
[shēng sǐ zhī jiāo] 生死之交: friends that are ready to die for each other
[huàn nàn zhī jiāo] 患难之交: friends in need
[jīn shí zhī jiāo] 金石之交: close and intimate friendship
[pín jiàn zhī jiāo] 贫贱之交: friendship from earlier days when one was poor