When you encounter the target large monster, proceed to start throwing paintballs at all the small monsters in the area. Explain it's to make sure they can't sneak up behind you.
Wear the jaggi mask and whatever 4 mismatched things you have that combine to look as bad as possible, but claim you chose your armor for looks and complain about how ugly the other players are with their matched sets and multiple skills.
Enter a room dedicated to a specific monster, and post a harvest tour quest (in an area that monster can't show up in). Whine about no one joining your quest.
Use a bowgun, and midway through the fight say "hold on, I ran out of ammo. I'm going to go fish so I can make more".
Use a lance and just keep running up to the monster and then standing there with your shield up without ever attacking. Brag about how good you are since you aren't ever getting hit.
Place traps while fighting an elder dragon, then start repeatedly pinging the map.
Insist repeatedly and unyieldingly on sleepbombing, but then wake up the monster by not stopping attacking it yourself. Explain you did so because you forgot to bring bombs.
Everytime your stamina goes down, loudly complain about it, then start bbqing some meat, and beg them to keep the monster off you while doing so.
Do arena fights, and focus all your effort on the tail. As soon as it is cut, immediately carve it, preferably getting hit while doing so. Then start focusing on other breakable parts, especially ones with low hitzone multipliers. Complain about your teammates not breaking parts, falsely insisting that doing so gets you more coins in the rewards.
Gem dungmaster into your armor, then throw a dung bomb the moment you encounter the monster you need to kill. Repeat after following it to a new area as many times as you can. Bring materials to make more dung bombs.
Try to mix armor and gem it so that you have 3 or 4 negative skills and no positive ones.
One more thing: use a lance and fight barroth or something else with a strong charge attack. Keep trying to counter its charge with your own. Use the lance charge against it as it charges at you, and complain when you get sent flying about how your charge should have staggered it.