Apologizing in advance, but this topic is in both the silly and inappropriate for children field. So, kids under 18, make the right choice and lie about your age before reading on.
When I first joined this fandom (this was when the anime was only about halfway out in Japan, and the manga wasn't all out in English yet), there seemed to be a strong perception that L was a very virginal character. I recall that L was most often seen by many as being an innocent character, too - I admit too that when I began my career as a Death Note fan, I was in the wretched "L is soooo kawaii!" team, before I realized stupidly that L is the opposite thing of kawaii (crazy badass muthafucka, harrr). Anyway, at first it's easy to think that L is sexually inept. After all, he sits on a computer all day, evidently has zero social skills, and acts like a moron around Misa. Not to mention his neglected physical appearance and (deliberately?) deviant mannerisms.
Yet, L's character consistently alludes to sexuality and even perversion. A lot of it he justifies as "part of the investigation", yet he shows absolutely no shame in doing it. In chronological order, examples I can think of this are: bugging the Yagami household with bathrooms included, grabbing Misa's butt to steal her phone, tying Misa up in very common hentai fetish way, handcuffing Light to himself (yet allowing Misa to wander more freely, when Misa's clearly the one who would give something away before Light). The author, Ohba, even recognizes this and has L called a pervert on a number of occasions, and characters question his ulterior motives (mainly from Misa, once when he has her tied up, and once when he chains Light to himself (the author even has Misa go so far as to outright accuse L of housing homoerotic feelings for Light)). L is a master of the "creepy hentai" face - the kind of guy you wouldn't want to turn your back to on a busy train.
Not to mention, L can-
..and he's also seen eating a banana in a perverted way while watching a make-up commercial done by Misa (to which Light says dryly "the commercial's over now, Ryuuzaki" when L is still attacking said banana).
All probability taken into consideration, L is human - he's most certainly not a little virginal angel (whether or not he's actually had sex or how often is one thing, but it's pretty doubtful that a 25 year old guy who is supposedly a genius doesn't know what sex is). To me, anyway, it's not even an argument - though it is kind of interesting when you think about it that Ohba possibly intentionally portrays L as the most sexual character maybe next to Misa, as another irony to his slovenly appearance and socially dysfunctional demeanor.
Ultimately, my real question boils down to this Youtube video I stumbled across recently:
Click to view
Was L fapping in the movie theater?!