N8CPA spelled it out right.
The "shave and a haircut" (-ESE) sequence was popular
especially with Novices, the licensees who had only
recently learned the morse code.
It's difficult to convey today the enthusiasm that
new amateurs felt during the 'Novice era'
(1950's-1980's), at the pride in learning the code
and becoming newly licensed hams. New hams would
toot out greetings to each other in morse on their
car horns, and so on.
The hobby has become somewhat more staid as it's
become easier to earn a ticket.
I liked the "shave and a haircut" tradition so much,
I changed my callsign to 'W5ESE'. You'll hear
several of us on the CW bands, with the 'dit dididit dit' callsigns.
The '-ESE' calls were particularly popular among
QRP operators, and we even had a quarterly contest
going for a while:http://www.io.com/~n5fc/barbershop_contest.htm