ha-ha Look up ha-ha at Dictionary.com
also haha, used of laughter since ancient times; Old English ha ha. Also in Greek (ha ha, in Euripides, Aristophanes), Latin (hahae). A different attempt at representation in English is py-hy (1580s). Sometimes interchanged with ah and expressing surprise, distress, etc. A ha-ha (1712), from French, was "an obstacle interrupting one's way sharply and disagreeably;" so called because it "surprizes ... and makes one cry Ah! Ah!" [Alexander Le Blond, "The Theory and Practice of Gardening," 1712].