Sometimes you need to stop what your doing, stop worrying about if a lift will carry over, ignore that its not part of the program and just have fun. The best, most scientific programs around will not produce the results you want if you are not enjoying it.
You need to remember why you train, and it should be because you enjoy it. It should be a release from everything life has to throw at you and something you look forward too, if you don't enjoy your training you will most likely not be putting in the same amount of effort, start missing sessions and limit your results.
Have fun, try new things you have never done before, variety is the spice of life.
This session had no reason, i had no idea what i was going to do other than having a bonus session. Turned up to the gym, looked around and decided i was going to try a few things and have fun which was a success!