Perhaps call round to one of your friends mums when toy know that the friend is out!
Only you can judge what is achievable from there! I would like to think that you could offer to do something of a good deed without it appearing too bizarre...

I don't really know her friends well enough to do that , how about something else along those lines ?

I dare you to put on one of your mums skimpiest pair of panties. You are then to go and visit one of her friends without any obvious reason but offer to do her shopping or clean her windows for her...