¿Qué significa “cair no gemidão do zap” ?

See a translation

There’s a silly WhatsApp prank among Brazilian netizens which basically consists of coaxing a friend into playing a super loud and cringeworthy clip of a woman moaning in a sexual way.

The person getting pranked gets the audio file disguised as a normal message (such as a voice message, a link to a video, an audio attachment, and so on). As they think it’s something relevant or desirable, they’re expected to hit the play button without putting much thought.

When the audio starts bustling out of the phone, it’s likely that other people nearby will start staring, giggling, or cracking up at the person holding the device. Even if the phone has its volume at a low level, the audio will still be fairly noticeable since its amplitude is edited up to make it as loud as possible. This will end up putting the victim in a tight and awkward spot, which is supposed to come off as funny to the ones pranking.

So, “cair no gemidão do zap” means, in other words, falling for the WhatsApp moaning audio prank.

📝 Breaking it down:
‣ cair em (fig.) ➝ falling for something, taking the bait.

‣ gemidão ➝ literally “a huge moan”, “a hell of a moan”.

‣ zap ➝ a slangish way to refer to WhatsApp (messaging app).