Talking Money.

They say money talks, but I currently have a five in my pocket that sounds like a pirate.  The serial number prefix is AAR.  Then again maybe it's a cry of pain, since the bill is torn in a couple of places.

Look at Canadian paper currency serial numbers and you'll see lots of combinations that make words, or some other familiar combinations of letters, depending on what you're familiar with of course.  Some familiar ones that have caught my eye include:

AOK, which looks like the phrase "A, okay!"
FET, which is a type of transistor.
APE, which is obvious.
FEM, which is sometimes used to indicate female. 
AOR, album oriented rock, a term often used for the big "arena acts" of the '70s and early '80s, like Styx and Boston.
HOP, another obvious one.
HOE, yet another obvious one.
HOG, as above.
BEV, the common short version of the name Beverly.
AOL, America Online, the Internet company.
APB, all points bulletin.
FEG, the commonly used trade name of Hungarian arms company Fegyver- és Gépgyár.
APC, armoured personnel carrier.
APU, auxillary power unit, found on  many aircraft.
AOA, Age of Apocalypse, a storyline from Marvel's X Men comics.
ANY, another obvious one.
HOT, yet again obvious.
BTK, the pseudonym of serial killer Dennis Rader.  Also a 1990s Canadian hiphop/rock group, Birth Thru Knowledge.
APG, a prefix used by the US military to identify aircraft carried radars ie the AN/APG-65 used by the F/A 18 Hornet.
AAA, anti aircraft artillery, or the American Auto Association.
BTU, British thermal unit, a measurement of energy use.
FEE, another obvious one.
ALF, both the short version of Alfred and the title character of a popular '80s sitcom.
FED.
ALE, as in beer
BTR, a series of Soviet era military vehicles, such as the BTR70 armoured personnel carrier
BTW, common online abbreviation for "by the way."
HOW, obvious again.
EWE, a female sheep.
ALT, a key on a computer keyboard, or an abreviation for alternate, or the last name of a famous model.
FEB, an abreviation for February.
AYA, a common Japanese female name.
EWI, Electronic Wind Instrument, a synthesizer controller, designed by Niles Steiner, for saxophone players.
AYE, obvious again.
AAM, air to air missile.
ARE, obvious.
AWE, obvious.
ALL, also obvious.
ARF, the sound of a dog bark.
BEN, the common male name.
ARC, another obvious one.
ARK, Noah's impossible to float boat.
ELM, a nice tree.
AHA, "A ha!"
ALA, "A la."
EVH, guitarist Eddie Van Halen.
BEM, bug eyed monster, a common '50s sci fi menace.
EVE, the girl who supposedly got us all in trouble.
ANT, a guy who was in Genesis once upon a time.
AVE, abreviation for avenue.
ELK, a nice creature to see.
BFF, best friend forever.
EVA, common girl's name.
FRG, short for the Federal Republic of Germany.
ERG, a unit of energy.
EST, a briefly popular New Age mental health treatment created by Werner Erhard.
AIM, US military prefix for air to air missiles. Quite appropriate given the word it also is.
BEA, common female name.
ASK, obvious.
GOB, English slang for spitting.
BEG, obvious.
ELP, Emerson, Lake, and Palmer, the popular, and sometimes infamous for musical excess, progressive rock group.
ERA, Equal Rights Amendment, which many Americans stupidly rejected.
GPS, Global Positioning System.

Yes, this post is silly and excessive.  But I just had to do it.