seeking info about a filler that appeared on Cartoon Network

[Roger Mateer]

hello

i have in mind a particular filler i'm pretty sure i saw on cartoon
network several years back (not sure exactly when). i've tried all
sorts of means of discovering what it was (google, wikipedia,
youtube), but have been unable to do so.

there's a depiction of a supervillain, i think his name was "Number
One", trying to conduct a meeting of the world's top villains when he
keeps getting interrupted by embarrassing phone calls from his mother.

he is drawn in a similar style to Space Ghost, except i think he wore
a grey-blue uniform.

at the end of the filler there's a depiction of concentric circles (in
blue and grey if i recall), and i think a 7 note musical flourish.
(i'm not musical, so i can't give any more reliable detail.)

does anyone know what i'm referring to? can you give me any pointers
to which show that might have been from?

every now and again i think about this, and it bugs me that i have in
my mind a snippet of popular culture that i have no way of finding out
anything more about using conventional internet searches.