Next time when you have sexy times, pleasure her as long as you can. Foreplay, penetration, some more cunnilingus, petting, really go the extra mile. When you're licking her, start also giving some slight attention to her butthole. A little in the beginning, progressively more towards the end.
No penetration, no fingering of the butthole (very gentle massaging at most, but it's best to keep your fingers off of it completely), but lick that hole and everything around it like your life depends on it.
It'll drive her crazy and she'll be begging for some action.