If you would like to remedy this situation, you will find that judicious use of the following three (3) comedic "stock phrases" will greatly assist you in changing that perception.
Note that you do not have to be "funny" in order to use these stock comic phrases. In fact, the comedic impact of these stock comic phrases may actually be enhanced if you are seen as not normally being funny.
You just need to recognize the trigger events (which can be achieved using rote memorization techniques) that will allow you to deploy your stock comic phrases to hilarious effect.
Ready? Let's begin:
Comic Phrase: "[He/She] isn't even breathing hard yet."
Setup Line: "[Subject] is coming/Is [Subject] coming?/Is [Subject] going to come?"
Why It's Funny/Comedic Mechanism(s): Sexual innuendo; Pun/Double Entendre /Exploitation of Ambiguity based on multiple definitions of "coming" [i.e. arriving/accompanying vs. achieving orgasm]
Usage Notes: Adjust as needed to fit situation and maintain subject/verb agreement
"The Redcoats are coming! The Redcoats are coming!"
"Don't worry, they're not even breathing hard yet."*
*Note the prefacing of the stock comic phrase with "Don't worry," referencing the original usage of the setup line as a warning or call to alarm. Recognizing the context of historical statements and being mindful of other, similar nuance will greatly enhance the comedic impact. Don't be afraid to modify these phrases to best fit your specific situation!
Comic Phrase: "Is it [day of week] already?"
Setup Line: Subject mentions extraordinary, uncharacteristic or otherwise atypical occurrence -- typically, an event of a sexual, scatological, violent, or sexually scatologically violent nature.
Why It's Funny/Comedic Mechanism(s): Implies deviant behavior by the speaker is actually part of his or her normal routine; use of irony (incongruity between expected and stated behavior); putdown (impugning the character of the subject, usually with good-natured intent)
Pop Culture Example:
"Man, I had a guy's finger up my asshole tonight."
"Is it Friday already?"
-- The Usual Suspects (1995)
Usage Notes: Be sure behavior described is generally seen as non-standard (deviant) behavior for that person.
Tip for Expert Users: Consider using longer measures of time: months, seasons, or even calendar years.
Comic Phrase: "That's what she said!"
Setup Line: Varies. In all instances, subject makes a statement that might conceivably be used in a sexual situation (i.e. a classic double entendre)
Why It's Funny/Comedic Mechanism(s): Calls attention to subject's inadvertent use of double entendre (Implies that similar phrase was heard by you during a sexual encounter.)
* Similar in nature to the stock comic phrase, "Is it [day of week] already?" although its usage is limited to dialog that might conceivably be delivered by a sexual partner.
* Must be sure that double entendre was not deliberately invoked by the speaker.
* Verbal emphasis should be on "she"
* Can be applied to situations that would reflect either positively or negatively on yourself (see examples)
"It was the biggest one they had ever seen."
"That's what she said." (Positive)
"Oh my god, I took one whiff and puked my guts out."
"That's what she said." (Negative)
Important Contraindications: Do not use the gender-reversed construction (female speaker, implied male subject), e.g. "That's what he said." This is because women are not funny.
With practice, you too can instinctively deploy these stock comic phrases and increase your perceived humor quotient!