Even though you verbally cast minor illusion, but unfortunatly the cleric's insight roll out numbers your deception roll and immediately calls out on your fake spell casting just to rip a loud one!

I cast Silence

How do I verbally cast Minor Illusion? It's somatic and material. 

You cast silence just before your compatriot was about to warn you that the BBEG was standing right behind you, leading to your untimely, but completely avoidable, demise. 

I cast Vicious Mockery

I edited my post it was supposed to be for the spell you backfired originally i just took too long...

the authorities arrest you for unruly behaviour

I cast Fear

You accidently target one of your allies and they run straight into a pit trap

I cast Fabricate

Your use of Fabricate violates ClerciPure(TM)'s registered patent on the bottle-manufacturing process. This leads to a civil suit that leaves you without house or home and in indentured servitude to a local feudal lord as you work off debt you've been put into as a result of the fine.

I cast Wall of Fire

You cast it in the middle of a tavern, forgetting that fire  can set things on fire, and now the entire town is in flames.

I cast Meteor swarm

The town elder says "I thought you were going to put out the fire that idiot* started, but you instead made it bigger!" and they drive you out. 

I cast Mage Hand

*"that idiot" being me from two posts back casting Wall of Fire

Your mage hand accidentally poked out the elders eye, and now you have the whole town guard after you. (Not like they weren’t already)

I cast FIREBALL!!!

The town elder sees you casting fireball, says "THAT DOES IT" and reveals himself to have been a shape-changed Adult Gold Dragon that is now out for blood. 

I cast Polymorph

You polymorph the enemy into a half-gold dragon t-rex.

I cast DoMInATe PeRSoN

The target has +20 wisdom saving throws, and rolls a natural 20, causing the spell to literally backfire and the target dominates you.

I cast Mordenkainen's Magnificent Mansion

As you're settling into your mansion for the day an irate tiefling shows up at your door. It seems you failed to submit the right zoning applications to erect such a structure. Furthermore, it also appears that you are actually trespassing on ClerciPure(TM) company property and they are presenting you with a Cease-and-Desist in regards to your (as for as the tiefling is concerned) attempted theft of company land.

I cast Charm Person

You accidentally charm your own mother in front of your father. Now she is in love with you and your father wants to kill you. Good luck, you’ll need it.

I cast prestidigitation

You soil the king's pants, and you are now up for execution.

I cast CREaTE FOoD AnD WaTEr

You heal everyone but yourself and the people you wanted to heal.

I cast iLLUSOry DRaGON

The dragon catches the smell of a large amount of very real treasure, flies off and attacks the nearest dwarven settlement, located in a mountain known as "Erebor", to claim their gold.

I cast shapechange to turn into a planetar.

You turn into a planetar. Other planetars see through your disguise, however, and gang up on you.

I cast create food and water, and create the world's largest roast chicken.

Ha ha. Very funnny

You inflict wounds on the person you wanted to cure.

I cast harm.

check the tooltip mwa ha ha

You target a creature with exactly 1 HP left, your spell does nothing.

I cast steel wind strike.

Sorry, What? I'll look that up, then edit... Got it! 
So, you disappear forever.

I cast [/Spell]Dancing Lights[Spell]

oh wait gotta roll for wild bc im a W.M.S. subclass and...(you choose)