Over the years I have come across several clients where being tickled has been a major trauma. It meant having their boundaries crossed and their body and excitement taken over without any means of stopping it. If later they indicate that the did not like or want this, then it is received as if they cannot take a joke or dislike fun.
Having one's body at the mercy of another unasked is of course traumatic as in sexual abuse, but with tickling it is also the deliberate manipulation of their excitement into a place where it goes over from pleasure, excitement and fun to invasion and fear or even terror as the object of fear is within - the effects of excess excitement on the system.
It may be in such families it is just one example of not being listened to and lack of empathic attunement by caregivers. It is an exercise of power over which starts as fun with but leads to an objectification of the other with the refusal of recognition of the traumatic impact. The victim is invited to laugh it off as well.
It is part of the normal adult interaction with babies to play with their excitement and give an experience of the thrill of some danger with the return to safety. This is often done by throwing the baby or small child in the air and catching them. I gather than men are more likely to let go than women and perhaps the role of the man is to expose the child to increasing risk as part of growth and adventure. However this is done within the frame of attunement and modulation of the level of excitement and the reality of the return to safety with a cuddle as they are caught.
With body psychotherapy with adults the question of what constitutes too much activation is harder to gauge. I remember many years ago a trainer saying to us that if you want to increase the flow of the river you need to increase the height of the banks; this was in the context of general working with energy. The general point is that the container of the therapy has to be strong enough to support the appropriate abandonment of safety in that moment with a certainty of return to earth; safety and the possibility of re-integration at a higher level with increasing ego-structure. We can only grow when we risk we can only know the strength of what we can test.
With tickling it is the child's weaker sense of self and their relative powerlessness along with the lack of attunement and empathy which is so destructive. Not being listened to and taken seriously afterwards, and often a sense of being played with, compounds the trauma. Tickling is one of the first self-other interactions which is why you cannot tickle yourself and can be formative or destructive. If in doubt about your abilities to judge another; don't tickle!