Yes, guys wear shower caps (whose gonna see ya anyway?)

The reason for the cap - it keeps the conditioner on the hair longer without it either being rinsed out while doing whatever else while in the shower, and it helps heat the conditioner (with your body heat trapped in the cap) which can help the conditioner work better.  You can do this every time you condition, or just whenever the mood strikes you.  A good conditioning will help prevent more damage to your highlighted hair.  

thanx bikerbraid-what deep conditioner do you suggest I use??  I'll try it out even if I look and feel odd in a shower cap