u/klnglulu

I was watching a documentary about con televangelists and they talked about a recurrent technique to create a sense of relationship with the people they are ripping off is to send them colored fabric and liquid and then have them send back (but with more and more money).

I got curious and wondered, is that action of receiving and sending back small pieces of coloured fabric or liquids something that some Christian groups do? or is it maybe based on some event in the Bible ?

I am not well versed in religion, I apologise in advance if the question is stupid.