Leggings that one can purchase on Amazon became viral on TikTok from people buying them and doing reviews. These posts were not paid and were just honest reviews about Amazon's leggings from actual. consumers. Girls across the world began purchasing these leggings based on TikTok's unsponsored reviews and friends who purchased and said how flattering they were. The spread of the famous TikTok leggings was due to what sort of promotional source?