What do the Leo shirts mean?

[Butters]

So far I've identified: 

Crew neck black shirt Leo:

Black dress shirt Leo:

White dress shirt Leo:

Fancy Leo:

[Nemra]

Different stages?

[Guest Nilsi]

I also recall Leo in a shirt and vest, elf ear Leo, masked Leo and Santa Leo.

[Phil King]

Evolution in content and communication style

[BlessedLion]

This is when following Leo gets unhealthy

[Yimpa]

Reminds me of this

 

[Butters]

10 hours ago, Yimpa said:

Reminds me of this

 

I think that's just random though, just using different images. 

Would be cool if there's any actual Easter eggs. 

[Agrande]

I think you’re reading too deep into it lol

[MarkKol]

It means Leo is becoming a wizard