I can take a guess here - is it the one used in the love scenes in "10"? If so, it's Ravel's 'Bolero'.
Underlying rhythm is
dum, du du du dum, du du du dum dum,
dum, du du du dum, du du du du du du du du du
If you're not a solo instrument in that one, it's the most boring piece of music ever written for orchestra. I'm a viola player - if my husband tried to use that to put me "in the mood", I'd be far more likely to run screaming into the street... :disgust:
Lady Niniane