Poised at the bottom of the stairs, though tugged back by Claire went he crept close enough to possibly be seen before Sam descended the stairs the entire way, Ben waited impatiently for his uncle to head toward the downstairs. Finally, footsteps on the stairs, first one set, then two, told him that they were descending, so Ben stuck the noisemaker in the corner of his mouth so he could still yell around it, then arranged the four poppers in his hand so he could pull the strings all at once.
A shoe appeared, then the rest of Sam, and that was when Ben jumped up and launched the confetti contents of the poppers.