The Number Neighbor (also known as Text Door Neighbor) trend involves messaging the person whose phone number is exactly one digit off from your own. While the concept circulated on Twitter as early as 2016, it reached peak viral status in mid-2019 when thousands of users began sharing screenshots of their interactions. These conversations range from wholesome new friendships and helpful advice to bizarre threats and immediate blocks. The meme highlights the unpredictable nature of modern digital communication, turning a simple numerical coincidence into a social experiment that captures the humor in reaching out to a total stranger living one 'digital door' away.