OK this isn't actually a question, just happened to me today and I thought it was pretty humourous. I'll post some exercises to make it a legit thread.

For rear delts I usually just use bands wrapped around a powerack and do reverse flyes. However, the other day I decided to switch it up and lay my stomach on a incline bench and do reverse flyes this way. After doing 3 sets with 20lbs (I guess form is pretty strict) I decide to do a superset. I go from 20, 15,10,5, and get about 10 reps each. Then I decide to drop the weight completely and just use the weight of my arms. Funny thing is I could only manage 5 reps. I just thought it was very humourous that I benched over 300 in the same workout, and then you could watch me completely strain with no weight in my hands doing rear delts. I recommend you try this once in a while