This month, WU’s oldest tradition, Thurtene Carnival, returns to campus.
A carnival was first held in 1907, and has continued annually. The only interruption came in 1943, when World War II called away many members of the Thurtene honorary. Otherwise, the weekend-long festivities, overseen chiefly by 13 students and always benefiting a local charitable organization, have consistently drawn together WU students and community members for over 100 years.
Thurtene Honorary began in 1904 as a society of junior men chosen based on their leadership and participation in campus activities. The society became co-ed in 1991. In its early years, it kept members’ names secret, publishing only a cryptic picture and the number 13 in the yearbook each spring.
The society’s annual carnival grew after 1935, when Thurtene took over the struggling circus hosted by the senior honorary, Pralma. Thurtene made the carnival profitable, enabling it to provide funds to campus organizations and local charities. The carnival quickly became one of the most anticipated campus events of the year and a favorite WU tradition.
According to one account, another tradition developed within the carnival: new pledges of the men’s sophomore honorary, Lock and Chain, were “always given a liberal ducking at the Thurtene Carnival. This provides great sport for the duckers and duckees alike, and is always popular.” 
(below, both) Thurtene Carnival program from 1991 and invitation from 1998:
For more information, see the online article “Thurteen Carnival” http://magazine-archives.wustl.edu/Spring04/ThurteneCarnival.htm
And the article “Our Once and Future Honoraries: Honorary societies Thurtene and Lock and
Chain are two campus originals, beloved by students since 1904” published in the Spring 1998 issue of Washington University Magazine.
 Hatchet, 1938, page 110