trolleys 
(also trollies)
plural noun British informal
Underpants or knickers.At Marks and Spencer's I bought a peach-coloured vest and trollies to match with insertions of lace....
- I mean, how fast will your desire wither when you see that tall, dark, handsome Lothario emerging from a cubicle with an Evening Times under his arm as he fumbles with his trollies?
- Knickers, underpants, trolleys or kecks, call them what you will.
Origin
Late 19th century (originally dialect): of uncertain origin.