Picking just 5 is tough! There are so many in this set that I think are fantastic!
I'd have to go with the following:
Souse Trap - Such detail! Love the drunks, but especially the little pink elephant, funny gags. Reminds me of Brandy Land.
Six Dollar Man - One of my favorite toys back then, I actually still have it. Good gag, excellent package, the font is perfect!
Apple Tacks - How was this never an OS Wacky? I love the old packaging with the two characters. Free detention inside is funny.
Bat - My mom drank Tab all the time. The package is great, great gag reversing the name, and I love the two pull tabs!
Pig Boy - I remember going there a lot. Great gag, the character is perfect, and the burger, condiments and sack are wonderful.
I hate leaving out these:
Grim - Another great gag, and a well-rendered jar. The lid is fantastic.
Stretch Armstrain - The gag here is perfect, as playing with this toy was great arm exercise.
100% Grating Cheese - Nice simple gag, and the packaging is perfect yet again. The guy holding his head is awesome.
Grave Poupon - Like the gag, love the jar.
Squint - This is just classic! I had forgotten about Squirt soda. Not sure I get the gag, but that was true with a number of OS Wackys that I always really liked.