Try tricept kickbacks!
1.Grab a dumbell in one hand and put the other hand and 1 knee on a flat bench
2.Point your elbow as high as you can towards the ceiling while leaving the dumbell hanging by your side
3.Slowly extend your arm until it is as straight as it will go (DO NOT change the position of your elbow!)
4.Pause for a second, then lower back to starting position
5.Repeat steps 3&4 for desired reps
6.IMPORTANT: Your upper arm and elbow should not move at all during the enter set. This is very important! If you cant do a complete set without moving your upper arm/elbow drop the weight off.