From OED
beano. slang.
orig. Printers' abbreviation of bean-feast. Later, in gen. use, a festive entertainment frequently ending in rowdyism.
1888 Jacobi Printers' Vocab., Beano, a slang abbreviation for _beanfeast', which is, however, usually termed _goose' or wayzgoose by compositors.
1897 N. & Q. 8th Ser. XII. 175/1, I can remember hearing a street song, some years ago, in which one of the lines ran something to the effect that We don't have a beano every day.
1914 Evening News 15 Oct. 4/6, I wish you could hear the men on their first morning in the hospitals._ _Fighting's a beano with this sort of thing for dessert.'
1920 W. J. Locke House of Baltazar ii, I'll get hold of Dorothy, and you and I and she'll have a little beano at the Carlton.
1924 Blackw. Mag. Oct. 494/1 There had been one of those awful last-night-of-leave beanos in town.
_1930 D. H. Lawrence Last Poems (1932) 269 O Pino What a bean-o! When we printed Lady C.!
1967 Listener 17 Aug. 205/3 Dear-heart, I fear we will have to make a token appearance at the beano those thrusting young String-Along's are giving tonight.