When I open up Safari, a figure in a yellow suit jumps down from the top of the screen

That is the "new" Apple home page screen animation. Started this week.

If it bothers you, you can wait until they get a another "cutesy" idea or go to Safari Preferences > General, find "New pages open with" and change it to another web site or an empty page.

EDIT: Just checked and it appears this little bit of entertainment may have run its course. Was doing it last night (Wed) but is back to normal-ish this morning.

Well, isn't that "special"! Can you post a screen shot? Use the Image Insertion icon in your reply window.

Aha, I'm not sorry I missed that. Men in Yellow, sounds like an alien menace!

Or the hazmat guys coming to clean my desk!

:)