well for the simple answer of "tyrosythesis" which is the vein in the penis that enables it to bend.
Why straighten it? Bend penises are a turn on for some women... just sayin'...
If by tilted you mean that it has a slight bend or curve either upwards, downwards or to either side when it is erect this is perfectly normal. The majority of penises have some sort of curve to a greater or lesser degree. Perfectly straight erect penises are in the minority.
As long as you have no pain and everything works well enough then there is nothing to worry about at all. Lots of boys and men have penises with bends in them. Some bend one way and others bend another way. Be proud of your penis !
some monkeys have penises
Swans are the only birds that have penises.
The fear of erect penises is called: ithyphallophobia.
All male cats have penises just like human males
penises. lots and lots of penises
No. These "penises" are called claspers, which deposit semen into the female shark.
No. Women like all kinds and shapes of penises.
Birds don't have penises! Birds don't have penises!
Penises?