I had a coworker last year who persistently tried to recruit me as his tandem surfing partner. This is what tandem surfing looks like:
The guy recruiting me is about 6' or so, and I'm...well, I'm pocket-sized. Big surprise then that, in this guy's eyes, we were Destined For Tandem Success. He then showed me a chart of tandem poses, which made me giggle maniacally, since it reminded me of Cosmopolitan's illustrations of sex positions -- both of which feature very flexible silhouettes. I'm not going to link or post anything here, but you could easily Google "Cosmo" and "sex positions" and witness exactly what I mean.
Ultimately, I had to say no to this guy because
a) I have terrible balance and flexibility,
b) this looks like a great excuse for a guy to grope his partner,
c) I'm not an exhibitionist,
d) he was married, but
e) the marriage was failing, and
f) I refuse to spend lots of time with someone who might be using me as an emotional escape route.
If he had been single and less drama-ridden, I might've reconsidered; tandem surfing, when you get past the fact that it's vaguely unseemly, is truly magnificent to behold.