From the Waterford Chronicle 21 October 1843 quoting the Athlone Sentinel:
An unfortunate female was thrown over the bridge at Mullingar into the canal, on Friday night, by some of her unfortunate companions, and was drowned. An inquest was held on the body, when a verdict of wilful murder was returned against six females, three of whom have been taken.
Irish waterways history 
Makes hen nights look respectable :( Mind you, Mullingar was always rough (lived there for 4 years).