Making a "break-away" whistle lanyard: whistle & lanyard
Go to Radio Shack and buy two sets of 1/8" RCA plugs/sockets (screw on sleeves). One set (a male and a female), for each side. If something hangs in your whistle lanyard, both sides break away and the cord doesn't go zingging around your neck.

Go back home.

Cut the original whistle cord (~1/8" od), on both sides of your whistle, about 4" above it (this produces four cord ends).

Lay out the cord in it's original shape and dedicate a male/female plug to each side.

Warm up a hot melt glue gun.

Un-screw the sleeves, pass the cord thru them and glue the end of the cord to/between the thingies that wires would normally be attached to.

Screw the sleeves back on over top of the now mated cord/plug or receiver (female).

Do this for all four plugs (two male and two female).

Plug the male ends into the females and WOW you have a "break-away" whistle cord!

Go to race track and blow.