moustache

[Mullins, Bill]

 From _The Tiger Claw_, yearbook of the class of 1929, The
 University High School, Columbia MO, p. 73

>From a description of attending a dance:

"The moustache was what made the hit with the girls.  Now, if you want to be
a mean, you can ask if it got in the way while it was making the hit, but
that wasn't what I meant.  I always have wondered why men wore those
miniature baseball nines on their upper lips.  But when I saw how the girls
liked to "fix" mine, I understood."

Miniature baseball nines??? What is the allusion?