Tatuajes literally translates to "tattoos." While it's a common word on its own, its use in this song is what makes it so powerful and memorable.
Junior H creates a beautiful metaphor, singing "Y tus besos son tatuajes, nunca se arrancan de mí" (And your kisses are tattoos, they are never torn from me). He uses the image of a permanent tattoo to describe how the memory of a past love is indelibly marked on him, an emotional pain that cannot be removed.
Junior H brings his signature sad corrido tumbado sound straight to a messy breakup conversation. The track starts with him holding his partner close while knowing it is basically over, saying "Baby, recuesta aquí tu cabeza en mi pecho / Hace ya meses que esto siento tenso" (Baby, rest your head here on my chest / I've felt this tension for months). He watches her pull away, pick fights, and change completely. His solution is blunt: delete the camera roll and toss the memories away with a frustrated "A la verga, se fueron nuestros recuerdos" (To hell with it, our memories are gone), even while admitting her kisses feel permanently inked onto him like tattoos.
The best part is the awkward confrontation with his ex's mother. The mom questions his sudden lifestyle shift, asking "que qué fue lo que pasó / Que me miró más tatuado, que qué es eso de 'sad boy'" (what happened, why she sees him with more tattoos, and what this 'sad boy' thing is all about). Instead of dodging, he gives her an honest answer: "¿Doña, qué hago si su hija me lastimó?" (Ma'am, what can I do if your daughter hurt me?). It explains the whole Sad Boyz identity in one sentence. He got his heart broken, added more ink, and leaned completely into the sorrow.