Disclaimer: This story might require a little constitution on your part.
When I was ~11 my mom was in a car accident in the family mini-van and it was totaled. While the insurance was sorting things out they gave us some 4 door sedan (for a family of 6) and the only other vehicle we had was my father's truck. So after about a month of having this sedan my parents decide it had been too long since we went out and did something together, "so tonight we're going to eat somewhere as a family". We decide on Chinese and have a good night at the restaurant. On the way back home the configuration of the car is as follows: my dad is driving, my mother in the passenger seat, my eldest brother (~15) behind the driver, in his lap my youngest brother (~7), in the middle seat was me and behind my mother my older sister (~14).
Now, as we're driving back a joke is told that has my little brother just cracking up, he's laughing so hard he starts coughing, to the point that he can't breathe and he starts having an asthma attack. So he is using his inhaler and he starts speaking through his little gasps, "Mom, mom, I'm gonna, I think I'm gonna throw up". My dad reacts instantly: "There is a garbage bag underneath your feet, find it". As you can imagine we frantically try to find this garbage bag but to no avail. So my mother grabs a to go cup from the front, dumps its contents out the window and says, "Throw up in this!" and hands it to my older brother. This all happens in a matter of about 30 seconds as you can imagine: my older brother is holding this cup and my littler brother starts throwing up in it to the point that it is overflowing on to my older brother who is sitting very stoned face and stoic, and on to me who is starting to gag a little. My mom, again reacting quickly says, "Give me the cup!" which she takes and again promptly tosses the contents of out the window. Here's the thing though, my sister had put her head out the window so she wouldn't have to smell the throw up in the car.
Not until the day I die will I ever forget the look on my sisters face when she pulled back into the car and turned toward me. It was a mixture of horror and apology, half covered in my little brothers vomit. It was smeared over exactly half of her face and it was so, so disgusting. In the split second she had, her eyes said to me, "I'm sorry, this is happening" and she unhesitatingly vomited all over both of us. Naturally, being covered in two different kinds of vomit and having just seen a face out of a horror movie, I instantly vomit on both of us as well.
My older brother just sat there, completely stoic. My mom is laughing so hard at what she's just done, that she is having her own coughing fit in the front. And my dad is yelling, "What the fuck is going on back there!?" He is pissed and this just adds to the hilarity of the situation. At this point we're on a pretty back country road so we pull over and strip down to nothing. My brothers and I are in our boxers and my sister is in our older brothers T-shirt (the only "clean" piece of clothing in the back of the car) and her underwear. My dad starts the car and then says, "I can't believe this", and my mom says "What, what's wrong?" and my dad says, "We are about to run out of gas". We are a pretty good way from anything so there is a real possibility we could be stranded in our current state, which just makes my mom laugh some more at the ridiculousness of it all. However, we do make it to a gas station, which affords us some pretty funny looks from strangers looking into the car at these naked children in the back. We make it home and after we get out under everyone's feet, we find a trash bag.