Here's a kinda stupid fic idea. So, a unicorn stallion accidentally casts an enchantment on his cock. The cock then glows with the color as his magic, and anypony to look at it just feels extremely compelled to follow his orders.

The idea is kinda early in development, and I won't be writing a story on it as I don't know how to make things work well. But still, might be a fun story depending on who writes it.