Andrew-(entering the kitchen where Mommy is washing dishes) Mommy, Ryan can't climb the stairs.
Mommy-You're right, he is too little. But he will learn how pretty soon.
Andrew-No Mommy, Ryan can't! Come here! (Leads Mommy to the stairs).
Ryan-(on the stairs, huge victory grin on his face)-AhAhAhAhaaaaaa
Mommy-Ohhhh....You're right Andrew, Ryan should not be climbing the stairs.
Here is the video of his first attempt. Not very action-packed, but documents his accomplishment.