A quick botch of a selfbot to add pumpkins to everyone's names in a server you have permission to do it in. (The commands are !addpumpkins and !removepumpkins)

pumpkin_nicknames.py

token = ""
# Insert your user token here.

prefix = "!"
# Here is the prefix. Feel free to change if you want.

pumpkin = "🎃"
# A unicode pumpkin.

import discord
import logging
# Imports discord and logging.

logging.basicConfig(level=logging.INFO)
# Sets the logging level.

dclient = discord.Client()
# Imports the discord client.

@dclient.event
async def on_ready():
    logging.info("Successfully signed into Discord.")
# Defines on_ready

@dclient.event
async def on_message(message):
    if message.author == dclient.user and message.content.startswith(prefix):
        cmd = message.content.lstrip(prefix).split(' ')[0].lower()
        if cmd == "addpumpkins":
            x = 0
            message = await dclient.edit_message(message, "We have started! This might take a while!")
            for user in message.server.members:
                if not user.display_name.endswith(pumpkin):
                    try:
                        await dclient.change_nickname(user, user.display_name + " " + pumpkin)
                        x = x + 1
                    except:
                        pass
            await dclient.edit_message(message, str(x) + " nickname(s) changed!")
        if cmd == "removepumpkins":
            x = 0
            message = await dclient.edit_message(message, "We have started! This might take a while!")
            for user in message.server.members:
                if user.display_name.endswith(pumpkin):
                    try:
                        await dclient.change_nickname(user, user.display_name.rstrip(pumpkin).rstrip(' '))
                        x = x + 1
                    except:
                        pass
            await dclient.edit_message(message, str(x) + " nickname(s) changed!")
# Defines on_message.

dclient.run(token, bot=False)
# Starts the selfbot.