1. Exhibits a rather exaggerated behavior.
2. Thinks too much of him or herself.
3. Narrates his or her anectodotes in an exaggerated way that usually makes him or her look good.
A close substitute of this expression is adornarse (lit. to decorate oneself). In sum, by adding sour cream to one's tacos, one make them look more appealing but not tastier. The essence remains unchanged.
Jefe de Recursos Humanos: Entrevistamos a más de diez candidatos al puesto. Todos le echaron mucha crema a sus tacos. Mejor congelamos la plaza.
Gerente General: Tampoco te adornes. Que se echen un disparejo y contrata al que gane.
Head of HR: We interviewed over ten candidates for the position. All thought too much of themselves. We better freeze that position.
General Manager: Don't exaggerate! Make them compete by flipping coins and hire the winner.