Well, I added a few slides to show diagrams of mouth shape when pronouncing the sounds, because I'm sort of a linguistics nerd and I thought the visual might help. By the time we got through the PPT show (well, or when I got through writing stuff on the board for us to practice in the room where the TV wasn't working), we didn't actually have time for the game. =\
In case anyone's interested in adding some linguistic/phonetic info to the slideshow, I'll go ahead and post the file that rencor27 originally submitted but with my alterations. For the B/P sound, I had students hold up the small piece of paper they had filled out for the warm-up activity (also posted by rencor), and with the paper hanging down, I had them pronounce the /b/ and /p/ sounds. Watching the paper move on /p/ helped them see the very noticeable difference between airflow if nothing else.
I also added a slide noting differences in the ways Korean and English syllables are formed. In Korean, they make the /sh/ sound by putting an 's' next to an 'i' leading to the 'Englishee' sound when they're not thinking about careful pronunciation. We don't have that consonant-vowel requirement for syllables, so we can make one-syllable words like strength or priest. I was somewhat impressed that even the low-level students had no trouble making the right sounds when they actually took the time to think about pronunciation.
The lesson went over well with the two HS girls' classes I have taught it to so far! They were middle and low speaking proficiency, so we'll see how this works out with high ability and also with my boys' classes... I may still have time to pull out that game after all. ^^
(TL;DR edition: Here's the slideshow a little bit longer with linguistic sound formation pictures as a bonus)