Green’s Dictionary of Slang

1. (Irish) the anus [hole n.¹ (1a)].

2001

G. Coughlan Everyday Eng. and Sl. 🌐 Swiss (a): Arse (swiss roll – hole) as in ‘Up your swiss’.

2. sexual intercourse [hole n.¹ (1e)].

2002		J. Cameron Hell on Hoe Street 52: Maybe not what you give some new bird when you’re after a Swiss roll, but good enough [...] on your tod.
2005		P. Howard Curious Incident of the Dog in the Nightdress 54: A focking geek who can’t get his Swiss in a brothel with a fistful of fifties.