Need more information to answer.
it means your still gong through puberty be sure to eat right and exercise
They have a hard penis...
it shouldn't be hard to get your penis hard. Try rubbing it, jacking off, thinking of sexual desires, having sex, getting a blow job. showing your penis to a girl. stripping.
Hard enough to remove your penis, as i found out (the hard way)
yes
Yes. They shrink when not hard
I hope not.
Good.
Yes anything over 6 inches is considered big but that depends if you are hard or not but you still are big dont worry :)
What to do when penis still in 4 inches even he is 21
Not at all.
erection