Giving a female friend a playful tickle in their sleep at some point in life, say, on a bare foot, is something I venture to guess most of us in this forum, even yours truly, have done at some point.
The issue I see here is the idea of the frequency of the tickling, and, especially, the foot worshipping part. Iam very much into female feet as well as tickling, and personally love to kiss and lick female feet, and suck on toes. This is only personal opinion here, but, to me, unless the person is a close friend with whom you have mutual agreement with first to do such activities with, that activity is usually most appropriate with someone you have some form of romantic, and sexual contact with, only. Even then, for myself, I might feel uncomfortable kissing or licking my girlfriend's feet in her sleep, if she didnt know I had a foot worshipping fetish. I would think that if a girl didnt know her man had such a fetish, and just awakened to her feet being licked, she might not be too thrilled. I would probably, at a comfortable point in the romantic relationship, explain to her about my fetish, and ask to kiss and tickle her feet. Many people, if they care for someone, unless they are really not into it, or dont want to bend or compromise for their partner at all, would probably try it to make their partner happy.
In the circumstance described in this thread: Believe me, I have a huge foot fetish, and I would probably love to engage in such activity were I in your position. However, the idea of you doing such to them in their sleep, when they have no idea what is going on, and they are not your girlfriends, personally makes me uncomfortable, and, it would seem to me, might put you in danger of at the least losing their friendship if they were ever to awaken and find out. I personally would seriously consider what you are doing, and proceed with extreme caution. Sometimes, what one has gotten away with, might eventually catch up with them.
Iam certainly not meaning my post to be anything judgemental, or scolding. On the contrary, I understand the attraction to worship female feet, even in sleep. However, the fact that you are doing so without their knowledge, just makes me uncomfortable, and I think might be putting yourself at risk. Think carefully, and proceed with caution, is all I will say.
Mitch