mob
    verb
        exploding_kunai()
            // Create a new projectile, and provide the player as an argument.
            new /obj/projectile(src)

obj
    projectile
        var/mob/owner

        proc
            move()
                while(step(src, dir))
                    sleep(1)

                // Conversely you can just do "del src" here as well.
                loc = null

        New(mob/m)
            owner = m

            loc = owner.loc
            dir = owner.dir

            // Spawn the move() proc off in a separate "thread".
            spawn move()

        Bump(mob/m)
            if(istype(m))
                world << "[owner]'s projectile hits [m]!"

                // Tell an explosion to show up where is standing and supply it with the delay argument, in this case 2 seconds.
                new /obj/explosion(m.loc, 20)

                // Pushes m backwards while still retaining their current direction.
                // turn(m.dir, 180) will turn the player around to the opposite direction they're currently facing, bypassing having to do that switch for FallDir you have going on.
                m.Move(get_step(m, turn(m.dir, 180)), m.dir)

    explosion
        New(newloc, n)
            // This is just an example but you can tell an explosion how long you want it to stick around before deleting itself.
            spawn(n)
                loc = null