By finding his various turn-ons. Some ideas are being very loving towards him, or causing him pain, or you could ask him.
He's a boy...
By getting naked
It is known as an erection. This happens once the boy has begun puberty. He will have an erection because of his readiness in nature to reproduce. It happens when he thinks of something that turns him on or through stimulation and randomness.
It is possible for a boy to get an erection from hugging a girl if he feels sexually aroused or excited during the interaction. Erections can be influenced by a variety of physical and emotional factors, including attraction and arousal.
It means he's male!
4 inches
When he looks at you, does he get an erection.
get ZAC FISHER TO RUB IT
Males are physically capable of obtaining an erection before they are born.
yes its normal
It depends if the guy is a pervert or not.
A "hard-on" or erection of a boy's penis occurs after he has gone through the life stage of puberty starting at about ages 11 to 13 (plus or minus). The penis turns into an erection when the brain tells it to - usually when the boy thinks about girls,but sometimes for no reason at all. It grows quite a bit longer (average 5-1/2 inches in length), thicker, and becomes very stiff and hard (Hence the term "Hard-on"). It points upward, anywhere from straight up to almost straight out. The erection will soften and go away when: 1. The boy has had sexual activity with others or by himself. 2. Enough time has passed that the boy has lost interest in whatever caused the erection. 3. The boy is startled, frightened, or sometimes when disgusted. The boy has no control of this, at all.