birthday pants and crotch rocket

[FRITZ JUENGLING]

This reminds me of something that I heard from one of my students recently.  When I asked her about her weekend, she went on and on about riding a "crotch rocket."  I was noticeably surprised that she would speak so openly and gleefully of this with her teacher and wasn't sure if she was saying this just to, if you'll pardon the expression, get a rise out of me.  Turns out, a 'crotch rocket' is a kind of motorcycle.  Of course, everyone knows this except for me.  Who would have known?!!
Fritz--who just isn't 'with it'

>>> zwicky at CSLI.STANFORD.EDU 01/15/05 10:00AM >>>
caught in the most recent New Yorker, "in one's birthday pants" 'naked
from the waist down':

At the same time, the stresses in the women's lives are played for
comedy (and sometimes as an attempt to get two laughs out of one
joke―in two episodes early in the series, two different characters are
caught outside naked, one in her full birthday suit and one in his
birthday pants).
-----

-----

and from yet another site, suggesting that "birthday pants" might refer
to crotchless pants (obviously not what was featured in "Desperate
Housewives", but possibly what the porn sites were going on about):
-----
http://www.oldskoolanthemz.com/forum/archive/index.php/t-13412.html