"Meep" expresses a cute but nonsensical exclamation.
The most well-known use of this comes from
Beaker,
the accident-prone lab assistant of Dr.
Bunsen Honeydew,
in
Jim Henson's
The Muppet Show.
Somewhat less well known, but more recent,
Goldie the
golden
gargoyle, from
Neil Gaiman's
Sandman
also used "Meep" as one of its few utterances.
Another animated character, the
Isz' from
Sam Kieth's
The Maxx also only speak the word "meep". Interestingly, the Isz exist as somewhat evil
characters, making their use of "meep" more of
an irony than a genuinely cute utterance.
[Thanks to Natasha_5 for pointing
this one out]