If you are looking for a specific title that fits this description, you might be thinking of one of the following:
A horror-comedy spoof where characters visit a spooky mansion for a will reading.
While "tiny teen bikini movie" is not the title of a single film, it likely refers to a of direct-to-video or late-night cable movies popular in the 1980s through the early 2000s. These films are often low-budget "sex comedies" or "softcore spoofs" that focus on beach settings, summer vacations, or outlandish parodies.
If you aren't looking for a spoof, your search might relate to these broader categories:
These films, often directed by (sometimes under the pseudonym Nicholas Medina), are the most common examples of the "bikini movie" niche:
A sci-fi parody about two waitresses who travel through history. Classic Beach/Teen Subgenres