Ghostbusters Response

Bad Bad Acting: In the commercial for Ghostbusters, the three Ghostbusters have ridiculously bad acting. The actors exaggerate the lack of acting skills of the zany scientists, making them seem completely unable to do a good commercial. One can only assume that the writers drew their inspiration from real life, as local TV is rife with these examples of horrible acting. From small car dealerships, to local hardware stores, these overly staged commercials are ever present.

Adorable Abomination: Gozer as the Stay-Puft guy is a great example of this trope, which is an example of a visual joke. The idea of the most evil threat to humanity be a giant puffy man is pure comedy. One example that I can think of is Spongebob's DoodleBob, a hand drawn Spongebob who wreaks havoc on Bikini Bottom. He is cute and looks innocent, but he can cause extreme damage. One other example could be the bunny from the animated film Hoodwinked, who turns out to be the mastermind behind everything bad going on.

Funny Background Event: As described by TVTropes, the prisoners passing by get increasingly interested in Egon's description of Gozer and Zuul. This is observable in well-known non-comedies like Star Wars and Lord of the Rings, and gag-filled films like Airplane and Men in Black. A possible source for this could be Hitchcock's North by Northwest, which was created in 1959.

Erotic Dream: There's no need to go into detail on this one, other than Ray is enjoying himself with a ghost girl. This will be my "hidden grown-up gag": Because of the way the scene is shot, this joke will fly right over children's heads. They could simply imagine that Ray is seeing a peaceful ghost, yet the parents in the audience know that something a little dirtier is occurring. As for the Erotic Dream trope as a whole, Fast Times at Ridgemont High has an excellent example (Brad imagines his sister's hot friend). As for origin, The Bitter Tea of General Yen has an erotic dream, and it is from 1933.

When talking to the Mayor, the Ghostbusters interject a funny bit of comedy-
Ray: Everything was fine with our system until the power grid was shut off by Dickless here. 
Peck: They caused an explosion! 
Mayor: Is this true? 
Venkman: Yes, it's true. This man has no dick.

This little dialogue is simple wordplay, so it can't really be traced anywhere. It is representative of the creativity of film writers, and it shows the range of ways they can make a scene funny. While this relies on language, other scenes employ irony or visual gags.