Current QuickPoll results for 1583 entries:
How the heck did the Geek stow away on the Time Machine?
He folded himself up like origami, ... his nickname's "the Crane".
He was hiding behind the fat TTB, ... not that hard to do, since he is only 1 pixel thick.
He shrunk down using the Time Machine's compression unit, ... luckily it uses a lossless compression scheme.
He hid in their luggage, ... is that why he smells so good now?
The Geek lied. He didn't stowaway, he was already there. You see, he's over 2,000,000 years old!, ... that's a lot of millenniums!
(May not add up to exactly 100% due to rounding, and missing links.)