Green’s Dictionary of Slang

1. large buttocks.

1508		Dunbar ‘Complaint to the King’ in Laing Poems (1834) I 144: With hopper hippis, and henches narrow, and bausy handis to beir ane barrow.
1686		‘Madam Le Croix’ in Wilson Court Satires of the Restoration (1976) 168: Thy hopper-arse will cause the fraction.
1704		W. King ‘Orpheus and Eurydice’ in Chalmers Eng. Poets IX (1810) 284/2: A lady of prodigious fame, Whose hollow eyes and hopper breech Made common people call her witch.

2. as a term of abuse.

1600

Dekker Shoemakers’ Holiday V v: Away you Islington white pot, hence you happerarse, you barly pudding ful of magots.