As their voice box enlarges and the vocal cords grow, their voice may "crack" as they speak. While this can be embarrassing and annoying, it's a normal part of the growth process.
Wet Dreams
Boys may wake up in the morning to find sticky, damp areas in their pajama pants and sheets.
Involuntary Erections
During puberty, boys get erections spontaneously, without touching their penis and without having sexual thoughts.
Breast Enlargement
Many boys experience swelling of the breasts during the early years of puberty.
One Testicle Lower than the Other
Uneven testicles, although they may be embarrassing in the boys' locker room, are both normal and common
Additional Information:
Additional Information:Boys' Secondary Sex Characteristics
Physical Development in Boys: What to ExpectYour Son's Changing Voice (Audio)