I think I saw this on Friends.
[hijack]
Joey: The first time I saw you I thought ‘great butt, nice rack’.
Phoebe: Thanks-well officially I’m offended-but thanks:giggle:
/[hijack]
I’d be shocked and offended if my friends (male and female) stopped commenting on my breasts. But we’re lascivious like that.
Strangers are a different story.
I think this just takes a simple look at the person and situation. For example:
Conservatively dressed woman passing the construction site where you work = Probably not going to appreciate the comment.
Good friend with large tits overflowing a tight corset who is laughing and chugging mead with you at the local RenFaire = Likely to take it well. Especially if you call her “Lass” and say it in a psuedo-16th century Scottish accent.
Substitute teacher wearing a shirt that is perhaps tighter than she thought it was this morning = Going to give you detention, and not the kind you were hoping for.
Boisterous and friendly gal you just met at a pub, who has already made more than one comment on her own breasts = May offer you another round.
The pretty blonde in a cocktail dress who has been avoiding your gaze all night = Hope she doesn’t carry mace.
Long time friend feeling bad about the guy who just rejected her and who needs cheering up = Well, hopefully you know her well enough to know if she’s going to laugh or cry over something like that.
If it was someone I didn’t know, I would not be impressed.
If it was my beau, no worries.
If some stranger told me I have “a nice rack,” I honestly would be confused. When I think “rack,” I think rack of lamb or a generic rack to hang things on. I don’t have a rack of lamb, and I’m not in the habit of carrying racks around.
However, I am accustomed to looking good, and I appreciate fellas and ladies respectfully complimenting my appearance. 
Y’all fellas need to just stick to complimenting the whole package. Tell the lady: “You look really nice.” Or echo DAVEW0071’s suggestion: “That’s a pretty outfit. It compliments your figure.”
Just as fellas are more than the size of their dicks, we ladies are more than just a set of boobs. It’s a package deal.
Would you still find it sexist if, for every time he complimented your breasts, he paid a compliment to his own penis?
I think my reaction would vary greatly depending on who said it. If it was one of my male friends I’d be amused. If it was a non-threatening looking stranger, I might thank him and make a stupid comment in kind; if it was someone who knew I wasn’t interested, or was something like twice my age…being ignored is the best reaction they could hope for.
i think the degree of my reaction would depend on who said it. if my boyfriend said it i wouldn’t mind, per se, about the sentiment, only about the words he used (which he wouldn’t…he uses much more flattering and romantic words than “rack”). it’s the term “rack” i have a problem with. excuse me, but i don’t have a bunch of pork ribs on my chest here. given, i’d find it a little odd if someone said “nice breasts” too, but i’d more take offense to the “rack” than to “breasts.”
my boyfriend may compliment me on my large breasts, my friends may comment if it’s in refence to some conversation we’re having. if it’s someone i don’t know at all, it sure as hell means i’m not going to be talking to that person. it tells me they’re only interested in my chest, that that’s what they’re looking at rather than my personality.
compliment me on my smile, my eyes, etc. not my breasts.
This always seems to be a bad idea if the lady in question is still fully encumbered by clothing.
If Twisty told me I had a great rack, I’d consider it a compliment. 
Seriously, friends are one thing. Random strangers something else. A guy friend is always complimenting me on my boobage. I’m not offended, because he’s not some scary random person. Plus, he’s happily engaged to a fabulous woman, so it’s not like he’s picking up on me or anything.
In the best response I’ve heard yet to such a compliment, the woman looked down at her breasts and said, “Girls, say thank you?” followed by a motherly “what can you do?” sigh and shrug.
What?!?! So you mean Madison Avenue has been lying to me all these years? Sob!
[sound of illusions shattering]
This comment wasn’t directed at me, but just had to respond.
Okay, so the situation as we have it set up:
Me at bar trying not to die from smoke inhalation, strange male approaches.
“Nice rack.”
Worry goes through my mind as his eyes size up my chest. He’s looking at my breasts, did I remember to wear a bra, am I even wearing a shirt? Something must be peaking, why else would a strange man tell me this? eek If I take my eyes off of him to check will he think I like his comment? I don’t like the look in his eyes, is he thinking about me naked?
Strange man looks down at himself. At this point I look down, and yes I’m wearing a shirt. I’ll have to make a bathroom check later to make sure I’m wearing a bra and nothings peaking.
“'Course being the stud that I am, I’ve got the package to match.”
He points at the slight bulge in his pants, he’s talking about his penis?
WHAT KIND OF SICK, SELF-OBSESSED PERSON BRAGS ABOUT HIS PENIS TO A WOMAN HE JUST MET? At this point I’d either run to the bathroom or latch on to a passing male hoping this will make him go away.
In all seriousness…this is a hard one to answer.
My female friends and I talk about our breasts, bodies, compare everything all the time. My male friends are okay to make comments about anything as well.
But a stranger? If someone’s complimenting such a specific, and sexual, body part… It generally means that he’s thinking of you in sexual terms. If this person creeps you out, and you definitely don’t want him thinking of you in any terms much less sexually it can be a bit uncomfortable.
Viv
There will always be a divide on this issue. Most women do not like the idea of a man they don’t know thinking of them in sexual terms; most men do like the idea of a woman they don’t know thinking of them in sexual terms.