Behind the Back BB Curls (EKG has proven this to be the best exercise for the forearms)
- Holds (with heaviest dumbells you can control, until failure or near failure if you cant drop DB's safely)
- Squeezing shit (my gym has a badass forearm machine that is definitely homemade)
- DB Wrist Curls
- Not using wraps
Hammer Curls work the bicep and forearm muscles too.