Manchester United will now think twice before initiating a social media campaign designed to publicise a pre-season friendly match before the new Premier League campaign kicks off.With the 2018/19 season set to start on 11 August, the Red Devils wanted to wrap up their summer preparations with one last game against a top club - just to get the juices flowing before what will be a testing season for Jose Mourinho and his squad.So what did their Twitter handle do? Well, they "put out an invitation to play a game in early August" against "a big club in Germany".We’re⚪️ Busy⚪️ On holiday🔘 Available in early August to visit a big club in Germany for a final pre-season game of the summer. Any takers?— Manchester United (@ManUtd) June 11, 2018Bundesliga champions Bayern Munich were quick to respond and that was when the trolling began. And they hit the English club how they knew best - by showing off their incredibly successful record in penalty shootouts.The only takers we’re interested in are for good penalties, and as an English club, you guys probably wouldn’t know about that... 🐸🍵 pic.twitter.com/7TJbc2V6lr— FC Bayern München (@FCBayern) June 11, 2018Not to be outdone, United hit back with a history lesson - their biggest win ever; the day they beat Bayern Munich 2-1 in the Champions League final with both goals coming in stoppage time to win a treble.Just as well that we didn’t need them to beat you in the #UCL final back in 1999 then, isn’t it? 🙄 pic.twitter.com/fllThHNaDd— Manchester United (@ManUtd) June 11, 2018Of course, that was 19 years ago and times have since changed. United haven't won a league title in five seasons now while Bayern have won the last six league titles in a row in Germany.Looks like we hit a nerve there! How about this pre-season friendly in August, then? Let’s hope your football is better than your jokes... pic.twitter.com/yePGKVTEIl— FC Bayern München (@FCBayern) June 11, 2018Obviously they had the last word. Or did they? Not to be left out of the banter match with nothing else to do this summer until the World Cup is over, other Bundesliga clubs also joined in.First up was Mainz - who finished 14th in the table. But that didn't stop them from replying to United's call for 'a big club'.Sorry lads, we're busy 😕— Mainz 05 English (@Mainz05en) June 11, 2018Borussia Mönchengladbach - one of the best Twitter handles for football clubs quickly replied too. They even changed their profile name to 'A big club in Germany' to rub it in!Guys, I think they were talking to us.— A big club in Germany (@borussia_en) June 11, 2018Bayern Munich's US account - another popular account - also got into the act.They're not ready to be #Stindled.— FC Bayern US (@FCBayernUS) June 11, 2018Finally, when Bayer leverkusen were asked to join the party, they had only one thing to say. pic.twitter.com/4JKUg2HzqM— Bayer 04 Leverkusen (@bayer04_en) June 11, 2018