Getting an erection like that is actually a sign of good health and good circulation. If you get embarrassed enough the erection will simply go away. When a man gets embarrassed or anxious his body releases adrenaline, a real chemical that actually shuts off the blood flow to the erection and kills the erection, and that’s the cause of physiological ed. For the record professional masseurs are trained to deal with arousal during massages as it happens all the time. So you don’t have to be self conscious. This is a normal part of the massage experience for most men.