What a shock!
From her co-star Chris Evans!
The actor totally surprised ScarJo on Thursday, sneaking up behind her and screaming "Scarlett!" which nearly made the beautiful actress jump out of her chair!
ScarJo was able to keep it together almost more than Chris, who doubled up with laughter after pulling the ultimate prank on his BFF!
Later, the two sat down with Miz DeGeneres to play a fun game testing their knowledge of one another, but it's clear from these videos that Captain America seems more than happy just to be able to play a few pranks on Black Widow!
At least she was a good sport about it all!
Ch-ch-check out a couple of videos from these two's appearance on Ellen (below)!!!