Me pegas un susto is a common everyday expression in Spanish, used when someone is caught off guard and wants to tell the other person they scared them. As a short voice clip it circulates online as a reaction sound, shared in edits and chats where the humour comes from the wording and the startled delivery rather than from a known film or show. Its appeal is its immediacy, because listeners who know the phrase understand the situation in seconds, and even others can hear the surprise in the voice.