嘿嘿 (hēi hēi) is an onomatopoeic interjection that imitates a light, suppressed chuckle—similar to English 'heh-heh' or a sly, amused snicker. Though it uses the character 嘿, which can mean 'hey' or function as a calling sound, the reduplicated form 嘿嘿 carries no literal meaning; instead, it conveys a subtle, often self-aware or slightly mischievous amusement. It frequently appears in informal speech and writing—especially in texts, social media, or dialogue—to signal playful embarrassment, quiet satisfaction, or knowing irony.

This expression is not tied to any specific action or object but reflects inner emotional tone. It’s commonly used when someone feels sheepish after a small blunder, enjoys a private joke, or teases gently. Unlike louder laughter like 哈哈 (hā hā), 嘿嘿 suggests restraint and intimacy—often implying 'I know something you don’t' or 'Well, well…' without saying it outright. Its tone is colloquial and friendly, rarely appearing in formal contexts.