This has happened to me twice now! I'm 7 weeks pregnant and only a few people know.
Last week I mentioned having a bad headache and before I knew it my auntie had ran off and returned with ibuprofen, out of the packet, which I then had to refuse and pretend it gives me stomach ache.
Then today at work, a new member of staff asked if I fancied helping him move some heavy furniture. My brain had a fart and I just went "not really" and walked away. Why couldn't I have made something up about having a bad back? He must think I'm so rude now.