My boyfriend is hiding something in his socks ?

Nk

The other day my boyfriend asked me to get socks for him, went to the sock draw and there was only one pair picked them up and it felt like there was tablets or something in there? But instead of looking I laughed and said what’s in here and gave it to him and he told me I don’t have to know everything which is fine but it’s just weird because why would he specifically hide it there! What do you think it is ?