Tā bùguò shì lǎobǎn de hǎbagǒu, yìdiǎn zhǔjiàn dōu méiyǒu.
He's nothing but the boss's lapdog - no opinions of his own.
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Strong figurative use: 哈巴狗 as an insult means a fawning yes-man - equivalent to English 'lapdog' or 'toady'. 摇尾乞怜 ('wagging the tail begging for pity') is the matching idiom often used to describe such people.
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哈巴 imitates the dog's panting 'ha-ha' sound, plus 狗 'dog'. The breed itself is the squat, snub-nosed Pekingese - historically bred for the imperial court, hence its association with cringing servility.