Gushpanka means hechsher, an imprimatur or seal of approval, especially one coming from an authority figure whose endorsement is highly valued. You might speak of Rabbi X giving his gushpanka to a book, or a food product.
Because the word sounds inherently funny to British ears, gushpanka is also used ironically. Rabbi X might then be giving his gushpanka to something that does not in fact require rabbinical approval, such as a political party or a football team.
One might assume that gushpanka, like other faintly humorous-sounding Jewish words, is Yiddish in origin, but in fact it is Aramaic and appears several times in the Talmud, where it means signet or seal.
Berachot 6a advises that in order to protect a certain precious dust from demons, one should seal it in an iron tube with an iron gushpanka. Gittin 57a tells of a Roman emperor who lit so many torches in his palace that the image engraved on his gushpanka was visible a mile away.
The ultimate origin of gushpanka is disputed. Jastrows Talmudic Dictionary posits that it is a running together of two words, gush meaning block, and panka meaning freeman or aristocrat the type of person who would have his own personal seal.
Rabbi Steinsaltzs translation of the Talmud maintains that the word is from the Persian angustpanak, meaning signet ring. The letter tav was dropped when the word entered Aramaic because of the rarity of three consecutive closed consonants (itzurim) in Semitic languages.