Green’s Dictionary of Slang

excused, be v.

(mainly school) euph. for to be allowed to visit the lavatory, usu. in interrog. phr. may I be excused?

B.L. Hatt ‘The Old One Room Schoolhouse’ in Tel. Journal 26 Jan. 🌐 ‘May I please be excused?’ I repeated, with desperation in my voice. Again she said ‘No’. Well I couldn’t wait so I did the only thing that any sensible kid in Grade one would do. I messed my pants.