Wash your hands of remembering the command to proxy a url through Browser Sync
Usage:
$ sink localhost:4001
Instead of:
$ browser-sync start --proxy "localhost:4001" --files "css/*.css"
Just add this to your bash profile and you're golden.
Note, you don't need to set up an alias; defining the function is enough.
sink() {
browser-sync start --proxy $1 --files "css/*.css"
}