What thing have you never heard of that a player tried to bring to the table?

[CyberThread]

(homebrew does not count)

What thing have you never heard of that a player tried to bring to the table and forced you to say no, as they look at you grumpily.

[Zero grim]

I didn't know about malconvokers until someone brought it to the table, I didn't say no to it because I rarely say no to anything that fits my setting, it was defiantly a fun experience seeing just how crazy thing became as soon as he decided to do anything.

I've brought rare and obscure spells/magic items to the table before but nothing really jumps to mind.

[sketchtb]

I started a campaign so my normal dm could play once in a while. Starting at level 1, I told him he could get any non magical gear he could afford, the setting was fairly exotic so I didn't have a problem with interesting new gear... Until he tried to bring in 3rd party 3.0 gear. Half goblin skin armor that has a 10% chance when hit to negate the damage and heal 1d6??? Had to drop the ban hammer on that book quick, it was full of non magical (bs) gear that was ridiculously cheap. So to get back at me rerolled a human fighter who took a vow of poverty and swung a club.

EDIT:
In his campaign, any published material is fair game with the exception of periodicals.

[John Longarrow]

1/2 golem template on a PC. Since it has a CR+ but no LA+ entry, he asked if he could just toss it on "Since there is no level adjustment"...

[Doc_Maynot]

Never have done so myself. Usually when I DM, I allow all 3.x (using the 3.5 version of anything in both) books 3rd party and otherwise and am strictly a RAW DM. (I fully accept all the potential breaky-ness in doing so.) But one time, when one of my players offered to master a game, I ran a Chaos Mage (Quintessential Chaos Mage). Needless to say, he wasn't happy about me using teleport to move allys and enemies around, and making all of our parties armour to adamanite (temporary of course) whenever possible, and especially when I turned his puzzle door to sand after an hour of trying to open it. Needless to say Manos, the Hand of Fate will be remembered, but will never see the light of day again. I now sometimes use chaos magic when making scrolls and wands (all named Manos' X) when handing out loot to give to players.

[Firebug]

As a player I brought Greater Mighty Wallop to the table as an Enlightened Fist Wizard/Monk. Next session it was house-ruled from 1 size increase per 4 caster levels to 1 size increase only. Apparently the DM did not like me Full attack Flurry-ing with 6d8 sized fists. And then casting a touch spell for free in the middle of a full attack...