What to call it or someone who easily laughs about something which isn't funny? [closed]

One of the meanings of risible is "having the ability, disposition, or readiness to laugh."

"Easily amused" for the first description. For the last description, "phony" came to mind but it's not really restricted to laughing. "Someone who fake laughs* constantly" is more accurate but then it's no longer a pithy description that you want.

*note that the "s" is on "laugh" and not "fake" as fake laugh could be used as a single verb (as seen in this Time article)

Also, if you meant "putting up a show" as "trying to appear outgoing in an annoying way"--and not as "sucking up to another person by laughing at their jokes" that "phony" describes--"loud" would be my single word for that, specifically with the Merriam-Webster definition of "noisy in a way that bothers other people".

"Overzealous laugher" is the best I could come up with to combine the two descriptions (and still keep it short) since it describes someone who laughs a lot in an unnatural, and perhaps vaguely insincere, way.

Edit: The "bit retarded" comment provides some context on what you're trying to say, specifically on the negative connotation that you would describe that person, almost to the point of mocking. In that case, "easily amused" might not be as negative as you'd like to, and the other definitions might not match precisely your intention. Perhaps you can use "lame/mindless/miscalibrated sense of humor" depending on how casual or negative you want to sound. How about someone with a "mindless laugh"?