The acute anxiety one feels accompanying a hangover following a night of excessive drinking due to a feeling that one said or did something remembered or unremembered that was ill-advised or embarrassing or may be construed by others as ignorant or abominable. Comes in doses. Likely to be of Corkonian origin.
Fiona dry-humped the boss in front of everyone at the Christmas party; she must have a terrible dose of the rats this morning.
I can't remember doing anything bad last night but for some reason I've an awful dose of the rats today.