I just wanted to second that nobody is going to have a problem with a 27-year old talking to (or asking out, or dating) a 22-year old. That's not a big difference at all.

I had always heard (as a rough guide) that the youngest you can date and be socially acceptable is something like "half your age, then add 7".

So, for a 27 year old, that would be: (27/2)+7 = 20.5. (Go ahead and drop the 0.5.) So, at 27, it's socially acceptable for you to date women as young as 20, if you buy in to the formula.

(And, interestingly, here's a brief article talking about age preferences for men and women compared to their own age, and how that formula works compared to the research. Neat. The Dating Equation: ½(your age) + 7 - | - Science of Relationships )