Half of Yakitate!! Japan's comedy comes from Azuma's new bread inventions and the completely insane ways that the rest of the cast reacts to tasting it.
Kurosaki gets orgasmic when eating McDonalds food in Kemeko Deluxe!
Burn Up Excess opens with a scene like this - we're meant to believe that Rio is engaging in some sort of sexual activity, considering the noises she's making, but then the camera pans out to reveal that she's just really enjoying her ramen.
The Jump shounen Shokugeki No Soma is made of this trope. You get it in almost every single chapter, by both men and women of all ages to boost.
Stocking from Panty & Stocking with Garterbelt only eats sweets. In "Sex and the Daten City", she's blogging about the "Pudding-gasm" she just had.
Toriko has plenty of these moments, being a manga full of Impossibly DeliciousFood Porn. Special mention goes to his first taste of Rainbow Fruit.
Sonny the Cuckoo does this every time he gets "cuckoo for Cocoa Puffs."
A PG Tips Tea ad in which Monkey's attempt to describe "The Taste" quickly turns into a parody of That Scene from When Harry Met Sally.
The reformulated Clairol Herbal Essences had endless examples of this.
Ladies in Dannon yogurt commercials often look like they are having orgasms.
As do the ladies in the 2010-11 York peppermint patty commercials.
A controversial (late night) UK TV advert campaign for Haagen-Dazs ice cream had women eating their way through huge tubs and getting more and more blatantly sexualised in their enjoyment of it.
Film
In The Matrix Reloaded, The Merovingian literally gives a woman an orgasm by sending her a slice of cake that has had its code altered.
Large amounts of Fan Disservice when a mob boss tries a new delicacy and pictures himself dancing on the beach in the sunset wearing not much and... yeah.
Also later when the cooking contest judge tastes Sorrowful Rice. Complete with an Imagine Spot of her rolling around on a chunk of BBQ pork.
In Beerfest, this is the reaction to the first batch of Schnitzengiggle beer.
In Ratatouille, Remy's eponymous dish is so delicious that it triggers Anton Ego's childhood memory of his mother serving him the same meal. He becomes a friend and ally of both Remy and Linguini from that moment.
This isn't what's actually going on in When Harry Met Sally, but it deserves mention here anyway since at least one person in-universe thinks it is. What's actually going on is that Sally is proving to Harry that she can convincingly fake an orgasm. While they're eating lunch in a diner. As Sally is winding down, a woman (played by director Rob Reiner's Real Life mother) says to a waitress "I'll have what she's having."
Discworld: Rincewind and potatoes. After spending some time on a desert island he got his appetites a bit mixed up, so that when a trio of breathtaking Amazons showed up looking for a man to help continue their tribe, his response was "can I get them mashed?" A footnote explains that after he returned to civilization, Rincewind's therapy involved a beautiful woman, a plate of spuds, and a board with a nail in it.
In Stephen King's novel Cujo, when a character in a commercial bites into a cookie "his expression suggests that he is experiencing the gastronomic equivalent of a boy's first orgasm."
Tairen Soul: The stimulant keflee has this effect on Ellysetta and Queen Annoura, especially when combined with pinelle. Taken Up to Eleven in one occasion when Ellysetta's latent magic is triggered by a particularly strong dose, and everyone in the room is forced to feel exactly what she is feeling.
Live-Action TV
In Firefly, Kaylee seems to really like that strawberry. She also fights really hard against River for a certain apple. Justified in that fresh fruit is a very rare treat for spacers, who often spend weeks on end in deep space.
Also, The Doctor (when Sharing a Body with Seven) and cheesecake.
Joey of Friends got this way about a specific meatball sandwich he rarely got to eat, and Ross also got this way regarding the post-Thanksgiving turkey-sandwiches his sister would make him.
30 Rock 30 Rock had the sandwiches that the Teamsters brought in only once a year.
Red Dwarf's Lister's relationship with curry is intense enough to qualify.
Food Network: The hosts tend to treat their creations this way.
There was an episode of How I Met Your Mother revolving around finding a shop that sold hamburgers which provoked this reaction.
Barney: That was so good I want to sew my ass shut.
Fridays: A sketch had cavemen (and cavewomen) having orgasms because of a batch of freshly baked muffins.
Seinfeld: George tries food to his love life. While he initially has success with strawberries and chocolate sauce, his girlfriend balks at a pastrami sandwich on rye with mustard. George surreptitiously does this anyway, but later gets caught trying to also watch TV while being intimate and she breaks up with him. Later at the coffee shop, George discovers that by trying to combine food and sex, his sense of hunger and his sexual urges have merged into one "disgusting, uncontrollable urge."
George: Gee, you're right...you gonna eat that?
Jerry: No, but please tell me that's all you're going to do with it.
Tang (of Tang's Weekly Comic) uses this as a gag to illustrate how you get across abstract concepts like deliciousness in a drawn medium—the character takes a bite out of a cake, and then proceeds to get a little too excited about it.
In Muertitos, Jesus really loves those donuts - rather embarrassingly to the protestors who had just been preaching about desserts being sinful. A few pages later, Kaori gets familiar with cake.
Web Original
Phase in the Whateley Universe routinely gets teased by his friends for his 'foodgasms'. (The background being a little deal he has with the school chefs; they get a rare opportunity to really show off what they can do and the benefits of being on the good side of one of the richest kids at school and he doesn't have to ruin his refined palate by settling for the standard cafeteria stuff.) Even those friends, though, have to admit that his 'special' treats are frequently just that good.
The SCP Foundation takes this literally with orgasm muffins
Serena from Sailor Moon Abridged orgasms while eating creme-filled donuts, and later again while likcing a vanilla ice cream cone.
In Maven Of The Eventide's crossover with The Nostalgia Critic, they spend a few minutes eating cereal. Guess who the camera focuses on looking like they've received a blowjob? And no, it's not her.
There's a Hanna-Barbera dog called Snooper who gets orgasmically happy when fed dog biscuits. To the point of floating up in the air, wafting to the ground, and sighing, "Aaahh."
"Floating" is not as apt a description as "launching". Like a rocket. Also, just in case his human companions had any doubts as to what Snooper wanted, he'd cue them in by opening his mouth, pointing into it, and saying "Ahh! Ahh! Ahh!"
Chris: Here Stewie, have a fig newton. (Stewie eats the cookie.) Stewie (while chewing): I say, I must use him for-oh my god, it's like an orgy in my mouth!
Stewie: What's this? Blueberries! Oh, oh my G ... oh, that's better than sex!
The Powerpuff Girls' first taste of hard candy causes them to "oh" and "ah" in a slightly sensual manner, then float in the air while giggling, then float back to the ground with their eyes half closed. If that doesn't sound orgasmic enough, Bubbles ends the sensation with, "that...was...amazing."
Similar enough to Snooper's reaction to dog biscuits to probably be a deliberate Shout Out.
A Pup Named Scooby-Doo : Happened whenever Scooby and/or Shaggy ate a Scooby Snack. The snacks were so good, they'd make the duo weak at the knees and instantly faint into bliss.
Video Games
Disgaea Infinite: When Laharl gets his hands on Super Rare Pudding in , he expresses its deliciousness with extreme delight and even has a hallucination of himself walking on a road of puddings in space! He had been starving himself all day long to fully enjoy the pudding.
Laharl: Mmhh, mmhh, mmhh, it's super delicious. This. Is. Sooooo. Goooooood.
The very first scene of Disgaea 4 is of Valvatorez eating a sardine. It does not sound like he is eating a sardine.
Valvatorez: What a splendid taste... The extract of life overflows and fills my body... I can feel it's power. Ah, the waves of ecstasy... How magical... are these insignificant creatures known as sardines!
In Leisure Suit Larry: Love for Sail, Larry wins a cooking competition by making a quiche that has this effect on the judges... because it's laced with "orgasmic powder".