Don't do that, it hurts
I guess I have to explain the means of learning from pain.
Much like a child learns not to put their hand in the fire, because it hurts and causes damage to the body we tell them "Don't do that cause it hurts."
So too we should learn from the indicators of pain in the jujitsu, judo, and Aikido practice that we do. Some people dance with pain expecting that their puppet show of childish screaming is the way to relieve pain, while most of us learn, and I reiterate LEARN, to go with the flow and learn to use ukemi to relieve pain to make our practice easier.
Maybe the lump is one of those who hasn't learned the lesson of going with the flow, and needs the slower lessons of doing the practice with instruction, and needs to be acquainted with the proper ukemi for relieving pain? I don't often see this, but every so often the Brain Fog is so thick it needs to be logically approached like a child that needs special help to catch up to the rest of the class.
If you understand that the use of pain is merely the validation of technique, as has clearly been put forth in more than one story about the early students of O'Sensei, then you begin to see the danger of practice ... and you will appreciate the safety concerns we have taken to make practice much much safer.
It doesn't matter if you are a gorilla, like me at six foot tall 285 pounds, which is continually proven moot by many smaller people who practice with me when they correctly stick to the classical style of Aikido which inflicts pain if I do not blend with techniques.
Last words of wisdom.
The first two weeks I started Aikido I found the grasps to be very firm, and a reticent stiffness in my partners. Coming from Karate/Jujitsu, the techniques were proven by the pain factor moving the uke and taking the slack out of techniques to be your margin of safety from offensive movements. My first partner was a younger ex Marine who was good natured but still depended upon upper body strength to muscle through techniques. At that time I had just finished working a constrution job, so I was in really good muscular condition for a forty something man.
We were doing shihonage, ura and omote, but I felt his arm getting tighter and tighter as it resisted the technique ... until after a few rounds I slipped and tried to pull him tight over my shoulder with muscle. You have probably heard a yelp of pain in your dojo at one time or another, and that is when the sensei comes over to see what is wrong.
I explained how tight this fellow was, and that there was a lot of muscle resistence. Now, being the new student the teacher didn't know how gentle the gorilla is or know me from Adam so he does a couple of shihonage's and tells the student, "you are using too much muscle to resist, relax, go with the technique." I have a lot more stories about nearly hurting some of my partners, but learning from first hand experience of being an uke in karate where teachers usually expect to induce twice as much pain as is ever seen in Aikido, I know from personal experience the difference in injury and discomfort.
Properly done Aikido will induce great amounts of pain if you do not learn to go with the technique, never go much beyond taking the slack out, or learn to have a sensitivity to feeling the amount of force needed in throwing / movement techniques.
Take the slack out, use your whole body, and give the lump a little time to blend.
Don't worry Opher, Kevin, I am just a middleaged gorilla without the temper of youth, and I lean more to laughing at myself these days.
Besides, my wife said I am not allowed to bounce people anymore ... takes all the fun out of growing old.