I was playing around with one of those translations Web sites when I discovered that “me falta” means “I need.” Of course, so does “necesito.” What is the subtle difference in shading between these two? Is one, say, more serious than the other?
Me falta = I am missing. . .
Necesito = I need. . .
Pretty much the same subtle difference as in English. Like “I need $500 to pay the rent” Vs “I am missing a card to complete the deck”.
Yep, sailor nailed it. But I believe one can also say “me hace falta…”
I think “me hace falta” is more like missing something, in the sense of “I miss you.” Me haces falta or Te extraño are both mostly “I miss you.”
Me hace
Me haces falta- I miss you
Me hace falta- I am missing
“Para bailar La Bamba, te falta una poca de gracia” (To dance the Bamba, you lack a bit of grace)? I don’t think so. The actual lyrics are “Para bailar La Bamba, se necesita una poca de gracia”. Similarly, the actual lyrics of “La Cucaracha” are “No puede caminar porque le falta… una pata” (He can’t move because he lacks a foot). “No puede caminar porque necesita una pata” (He can’t walk because he needs a foot) would be a weird way of putting it.
“Necesito” means “I need”, “me falta” means “I lack”. They have basically the same shades of meaning as in English. They overlap a bit, but “necesito” can be used to refer to something which one has: “No, no puedo prestar mi coche. Lo necesito.” (No, I can’t loan my car. I need it.) “Me falta” always refers to something that one lacks, but does not always refer to something that one needs: “No, no soy un pajaro. Me falta alas”. (No, I’m not a bird. I lack wings).
So, it isn’t “Me falta a blowjob,” huh?
Unless you’re counting them… and came up one short…
Now, think. Where did you last see it?
No, that would be “me hace falta una ******”
There. I can’t say that word.
The original thing the cucaracha was lacking was not a foot but:
“La Cucaracha, la cucaracha
Ya no puede caminar
Porque no tiene, por que le falta
Mariguana que fumar”
Yep, mariguana as in marihuana! The roach could not walk because it was missing the bong! 
For years, I thought it was the “foot” but I read about the history of the song, and the most shocking thing I remember was watching a clip of little Shirley Temple (circa 1930) singing the song with the marihuana line on it! :eek: