The 'That Was a Grown-Up Kiss' meme stems from a highly debated and emotionally charged scene in the anime Neon Genesis Evangelion, where the character Misato Katsuragi kisses Shinji Ikari. Intended to be a gesture of motivation or a complex farewell, the line 'that was a grown-up kiss, we'll do the rest when you get back' became legendary for its awkward and sudden shift in tone. Online, the meme is used to represent moments of sudden maturity, the harsh reality of 'adulting,' or any situation where someone is thrust into a sophisticated or intense scenario they weren't prepared for. It captures the universal feeling of being stunned by an experience that marks a loss of innocence or a transition into the complicated world of adults.