First time I sat on one thought "yeh this'd be ok" then riding an ER5 doing my lessons thought "this isn't too bad" then when I picked up my first ever road bike (R6) and pinned the throttle I thought "F**K what have i done!!!!"
But never looked back since...
Then you've got your first burnout, wheelie, stoppie etc etc......
Bikes, can't beat em'