UPSIDE DOWN can be spelled upside down using right way up letters of the alphabet:
umop apisdn.
Note that this only works if you use a font with a "double-storey" "a" - which is to say, if you use a "single-storey" font like the notorious Comic Sans, or anything in italics, it doesn't quite work:
*umop apisdn.
*umop apisdn.
[daily log: walking, 6.5km]