immature

At first he doesn’t accept her apology but, being the immature oaf that he is, Chris gets back at her by using her as human torpedo to destroy their gooey, disgusting alien target.

It was the act of an “immature, emotionally disturbed and mentally ill youth” who had killed in a trancelike state, said defense attorney Emil Berman.

Like all young players thrust into the limelight, White admitted Hampton was a "little immature" when they first played together at Birmingham.

"People see young women as weak and immature but we will grow up - and then the world will change again."

As a group, they’re immature, incompetent and naive, not without good qualities but prone to misunderstandings, mistakes and mishaps, which as characters in a sitcom they can scarcely fail to be.