cottage, adj. — Green’s Dictionary of Slang

cottage adj.

[? the perceived inadequacy of such a rural dwelling]

(US campus) bad, second-rate; eccentric.

1970		Current Sl. V:3 5: Cottage, adj. Eccentic; ‘lunchy’; strange.
1997–2001		Online Sl. Dict. 🌐 cottage adj 1. bad, old, worn-out, or stupid. A general derogatory adjective. (‘That stuff is cottage.’).