5 or 6 "S's" for "don't have to wear your pledge pin when...

[naraht]

I've seen the term "5 S's" or "6 S's" used to describe the conditions under which a pledge is *not* required to be wearing their pledge pin. I can remember four of the five, but I'm not sure which one I'm forgetting..

Sleeping
Showering
Sweating (exercise)
Silk (certain good clothes which would be damaged)

Note, from 5 to 6, I do remember that you add 'Sex', but I'm pretty sure that it isn't the one missing from the 5. Also, does any group (presumable a sorority, due to using the term 'Silk') actually use this list in the 5 S's form? (I presume that the 6th S, wouldn't be used in any official capacity)