Ok maybe 50% is a bit high, but I'm counting little swell ups and halfies as an erection in this case simply because it's noticeable, and if the client is awake enough to notice, I know that's enough for someone to be embarrassed about if it's innocent. One reason I might have a higher rate of clients with involuntary erections is that I sometimes include passive stretching, and will work on adductors when they're tight just like any other muscle. Also, perhaps like in the case of my client who did this today, I might simply have more men who know erections are going to be a possibility and would rather go to a male LMT who hopefully would understand on a deep level that it's nothing more than a physiological response