what tip do you give on a $14 pizza?

For shitty service, NO tip is definitely acceptable.  That way the driver or person in the restaurant business knows not to screw up and take you for granted the next time.  Just tell him you normally tip well, but the service sucked.  He knows you are right and will be angry with himself, not you. 

And for a $250 order, the 20% rule still applies ($50 tip).  Thus, in this scenario, a $20 tip would be insulting.  Anybody should be able to figure out 10% in their head and just double that number.    

 Make sure you give it to the phone person (usually a high school girl) if at all possible, cause they are the direct link to your order and get paid crap wages.  The drivers and the managers already make enough money, so they do not deserve a tip IMO.   

That's great, as paying customers, we are already being profiled as we walk in. 

How much do these waiters make?  They must make about $1000 a night at a nice restaurant.

A waiter should be tipped based on service which is called work.  If I had quite a few people with me, I wouldn't mind tipping more than average tip rate since waiter did more 'work' compared to him only serving 2 people that requires less work.

even if its slow and the service is taking forever  and she messes up , i will always give around 20% ... Some people have rough days, ive been there  so even if she/he is a bit rude ill still give 20% tip.   It would have to be really awful service and she/he would have to be pretty mean for me to give less tip.

 Bad Tippers should realize that most of these people live off their tips.  Most of them are trying their best to serve us.  Lets not be cheap here...

By the way, my post was more based for restaurants but pizza delivery does apply i guess.

Even if the service is awful/ example the cook fucked up the food or the order was taken wrong from whoever used the phone then its not the drivers fault so a tip is definitely warranted still.

Order is correct, overall good+ quality, and reasonably quick delivery...then give the poor guy a $20 and tell him "no change my man, thanks and have a safe night".  

Reason? One word....KARMA

I delivered pizzas for too long, and I completely disagree that a tip is always warranted.  I delivered late pizzas at a decent rate at my last job due to COMPANY incompetence and regular understaffing.  And I finally got fed up with telling the company to hire more people in order to keep from driving in every direction.  When the customers rightfully complained, I let my COMPANY know my displeasure, but to no avail.  And if the customer is frustrated, as a REPRESENTATIVE of the company, I accept full responsibility and deserve NO tip.   

Wow guys... $2 or less, really?! $3 min for a delivery tip. What is the convenince worth to you? I never have understood why people don't tip appropriately or at all (you're garbage if you don't tip when you should)... unless the tip is included (a 'service charge' doesn't usually mean that it goes entirely to the driver)

You're 'tip' is paying that individual for their service(s). If you don't want to tip, stay home and eat or go pick up your pizza you own cheap self.

Your use of delivery people and wait staff/bartenders/etc. are an added service, not a right. Have you ever walked out on a check?