Kàndào tā chénggōng, wǒ gé zhe píngmù gěi tā bǐzàn.
Seeing him succeed, I threw him a thumbs-up through the screen.
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比 = 'to make (a hand sign)', 赞 = 'to praise / like' (also the WeChat 'like' button). 比赞 is the casual, screen-era cousin of 竖大拇指 — shorter, more performative, photo-and-video-friendly.
