Agree with J_9 (unless you are getting rather kinky with your smoking habits - a la Monica Lewinski :eek: ). Someone once asked me if it were possible to either get pregnant or to get an STD sitting on a toilet seat - I told them you most definitely could - but it would likely be somewhat uncomfortable for both you and your lover... ;)
Herpes simplex type 1 (HSV-1) is usually associated with oral (mouth) lesions and type 2 (HSV-2) associated with genital lesions - but that's not always the case. The viruses are very closely related and you can transfer HSV-1 from your (or someone else's) mouth to your genitals by touching a cold sore and then touching your genitals - or through oral sex. Likewise, HSV-2 can be transferred from genitals to mouth in a similar manner through touch or oral sex. Shared oral objects - cigarettes, toothbrushes, silverware, etc - can possibly spread whichever virus (HSV-! Or 2) is residing in the infected person's mouth to yours. See this link for more info...
http://www.herpesonline.org/articles/herpes_virus.html