Six Flags Fright Fest

A commercial for the Fright Fest of Six Flags is a video aired in 2016, with a unique placement for a screamer.

Commercial
The ad starts as a normal ad, with people enjoying the park, and a woman voice over saying "There's something for everyone at Six Flags". However, exactly 3 seconds in, a monster clown appears and roars, before cutting to creepy imagery and a different male announcer advertising the haunted attraction for the rest of the ad.

Link
NOTE : The following video contains a screamer very early on, and you better be prepared when entering the link.
 * youtube.com/watch?v=H0BrPLhTjt8