This will do the trick.

Mayonnaise?

You're going to put mayonnaise on my head?

Sure.

It's what your grandma used on me when I was a kid.

Ugh!

That was when I had head lice.

Not a good day.

You ever notice how it's easier to remember bad days than good days?

Here are my top five worst days ever.

Number five.

The day I was fired by my piano teacher for not practicing.

Did you practice?

But I did practice!

Kind of.

A little.

Oh, not really.

Good-bye, Arthur.

You're fired.

(gasps) ARTHUR: Number four.

The time I ripped my pants in school and everyone saw my underwear.

(kids laughing) ARTHUR: Okay, we don't have to see any more of that one.

Number three.

The time Buster left for his trip around the world.

He was gone for a whole year.

BUSTER: I bet I'll never find another tree house that can fly to outer space and go back in time and become invisible like that one.

It'll still be here when you get back.

Yeah.

Good-bye!

Good-bye, Arthur!

ARTHUR: Number Two is actually a whole lot of days put together.

(gasps) You took my snowball!

I know you did!

Where'd you hide it, Snowball Thief?

I want a confession.

Confess!

Confess!

Confess!

But the number one all-time worst day ever was when... (baby crying) Ah!

Hey!

What?

That's not supposed to be on there!

(laughing) Isn't wittle Arthur cute?

I think I may have just found a new worst day.