You can use saucy to describe someone who likes to cause trouble, but usually in a playful and funny way. Saucy is also a good word for a person who really likes to flirt.

In the novel Oliver Twist, the character the Artful Dodger goes to court for stealing. During his hearing, the ten-year-old screams, “I am an Englishman; where are my rights?” Saucy words from a saucy child. A saucy comment makes people gasp because it’s surprising and a little dangerous, like talking about witchcraft in front of a priest. Saucy also describes a person who flirts with very sexual language, which can be fun, unless your grandparents are nearby, which is awkward.

Definitions of saucy

adj improperly forward or bold

fresh, impertinent, impudent, overbold, sassy, smart, wise
used of temperament or behavior; lacking restraint or modesty

adj characterized by a lightly pert and exuberant quality

impertinent, irreverent, pert
displaying animation, vigor, or liveliness