rantan
»A quite rational person: When not on the rantan.» (They And I. 258. 9.)
A schoolgirl.
On the rantan (or randan) means the same as »on the spree»—which does not directly imply tipsiness, but a degree of exhilaration practically unattainable without considerable indulgence in alcohol.
The expression is probably derived from the verb rant: to talk big, high, to boast much.
Cf. to go on the rantan: to go on a round of debauchery.