A discussion at Dr.Katte’s blog that is worth your time. It may not make much sense to you if you are not aware of the religious marking that hindus, particularly those in south India wear (not all). I applaud both Dr.Katte and the student for conducting the discussion openly.
Marking oneself ritualistically is not something that’s confined to religion alone. There is also a wide degree of variability based on culture, personality and whetever-else-there-is. Some are severe (Link not for the squeamish). Some really funny. And many not worth bothering at all.