Just after dinner and before a couple of after dinner drinks tell her to nip aff to the loo and take her knickers aff and show you them in her handbag when she gets back.
You'd be surprised how often that works.
she left my bit on sunday there with her knickers in her handbag. My brother was washing my motor while she was doing the old walk of shame. The temptation to shout "Haw [insert brother's name], she's wearin nae knickers!" was strong but I held back.

