Strange locale behavior

[David Baron <d_baron@012.net.il>]

Perl keeps giving locale errors so here is this:
$ locale
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG=en_ENus
LC_CTYPE="en_ENus"
LC_NUMERIC="en_ENus"
LC_TIME="en_ENus"
LC_COLLATE="en_ENus"
LC_MONETARY="en_ENus"
LC_MESSAGES="en_ENus"
LC_PAPER="en_ENus"
LC_NAME="en_ENus"
LC_ADDRESS="en_ENus"
LC_TELEPHONE="en_ENus"
LC_MEASUREMENT="en_ENus"
LC_IDENTIFICATION="en_ENus"
LC_ALL=

So what is it looking for?