Boyish Charm
Personality traits in an adult male that are more often  associated with pre-adult males. Women often succumb to boyish charm due to their inherit attraction to children. 'Girlish charm' is not used much (if at all)because men are generally not attracted to women who exhibit personality traits of pre-adult women.
After Tom pulled a yo-yo, a piece of string and some bubble gum from his pocket, Sally knew his boyish charm would win her over.