Depends on age.

Some girl teenagers love, clothing, electronics such as cellphones, Ipods, laptop, or maybe a makeup kit, or even a craft kit. Give them a gift based on their hobbies mostly

Some boy teenagers like gifts musical instruments, clothes, and most of all ADIVCE.

You know how boys love girls so give them ADVICE that could be enough for them, help them understand girls and if they like one give them the gift