I am the only one I know who is embarrassed when I catch myself
unconsciosly licking my lips in public.  This is because, (as my
sister and ex-boyfriend pointed out to me years ago), the underside of
my tongue is unusually "blue" & unattractive looking. My guess is that
it's veins that create this blue effect, but my question is: How
common or normal is this? What is it really due to? And is there a way
to make it pinker for imortant events?  Thankyou!

Perhaps if you just refrained from licking your lips at important
events the need to dye a naturally colored organ wouldn't be an issue.
Try some chapstick or lip-gloss for a change and let us know how it
works for you.

Regards;
tutuzdad-ga

Making remarks like that is probably why he's an EX- boyfriend,  I
guess. (Sisters you're stick with.)

I don't think you need to worry unless your tongue is white and furry
on top. Most people won't even notice.

I've just checked everyone's tongue in my household, even the dog's,
cat's and the blue tongue lizard's -- (I'm quite serious!) Out of the
ten tongues in this place, we all have blue undersides to our tongues
and the blue tongue lizard's is blue all over ... and very attractive
too! We think that the blueness is due to the fact that we're pumping
blood and as long as we're doing that (and our faces aren't turning a
similar hue) then all's well with the world. Don't need to know much
else. Good for you that the boyfriend is an ex, and re: your sis,
remember, it's in that well worn but top secret publication, "The
Sisters' Manual of Terror and Torture", that sisters are put on this
earth to undermine, ridicule and generally upset one's siblings at
every opportunity. Your sister is obviously doing this well. Maybe you
could point out a small but weird birthmark on the back of her neck
that is only visible to her if she turns her head 180 degrees. She'll
be so fixated on that, she will forget all about the colour of the
underside of your tongue (I mean, puhlease!), but if by some devilish
chance she can spin her head right around, then maybe you should
move!!!