A classic soln if you think you might change your mind is to copy the original file to that with a date/timestamp of when you did it eg
cp /etc/hosts /etc/hosts.20151109_1205
NB: this format (YYYYMMDD_HHMM) sorts naturally in ls etc.
Personally I'd be wary of altering a cmd to do something nonstd; you might break script somewhere (not to mention fill up your disk).
It might be an idea to instantiate the above as a fn in the login script as eg
rma /etc/hosts # 'rma' = custom rm for AdultFoundry
and just get in the habit of using that.