Is it true that women can apply testosterone cream to their vaginal area to increase sex drive?

1) What are the long-term and short-term effects of abusing NyQuil? I've heard it's very dangerous to use it recreationally, but I'm not sure what's dangerous about it. I've heard you can even die from abusing it.

2) I have recently just finished my first year in college and on a few occasions, a couple of friends and I had decided to drink massive amounts of Robitussin DM (dextromethorphan, I believe). It was fun, but the day after I felt like I was hit by a car! They call it robo trippin'. I have no intentions on doing this again; however, I was wondering if there were any long-term effects of it.

I like to use codeine occaisionally (once or twice a week at most) to help me relax and feel a minor high. Typically, I'll take about 90 to 150mg per session (100 to 200mg per week on average). Sometimes I take Tylenol-3's, and sometimes I extract the codeine from these pills and drink it pure. What are the potential health side-effects of this usage, both short- and long-term?

Thanks!