Fractional Jet Captain reported the Tower Controller spoke unprofessionally and berated and reprimanded the flight crew due to a miscommunication and then deliberately delayed their takeoff clearance seemingly as punishment.

Narrative

Angry Controller. We were preparing for taxi and takeoff. The runway had changed and we were preparing the avionics adjustments and briefing while taxiing. I am also doing IOE (Initial Operating Experience) with a new student. Upon reaching the approaching the end of the Runway XXL in ZZZ my student calls the Tower to notify of our readiness for takeoff. The Tower Controller keys his mike and talks over him and interrupted his transmission. My student; thinking they had accidentally interrupted the Tower; transmits our readiness again. The controller then reprimands them for calling and used very inappropriate language and an angry style. It was completely unwarranted. The controller had been communicating with everyone in an aggressive and inciting tone. We had commented about it during our taxi. While I was briefing the new departure I thought my partner had missed a call so I replied back. Unfortunately Tower was talking to someone else instead of me. I apologized to the Tower for taking someone else's call.Later the controller told us 'finally!! you are up next.' Then proceeded to ask us why we had' interrupted him and cause so much confusion for him; taking other aircraft's calls and what was going on?' I was confused at the series and tone of questioning and stated that I did not know what he was talking about. I think I did know; but that was not the venue to have that type of discussion or create a debate or argue about it nor was it the appropriate professional tone to use. In his anger; he loudly reprimanded me again and stated 'You don't know what I am talking about?' I paused; then to the controller I stated 'let's keep this professional' hoping it would create a more calming environment and situation and diffuse his angry moment. It seemed to work. After that he had told us we were up next to take off; however; he allowed one or two more planes take off before us. I felt he was delaying us deliberately at that point just to punish us. I feel that type of behavior is unprofessional; uncalled for; and unnecessary.We had a company VIP onboard who was very anxious to go and it was stated in ours notes of the time critical nature of the flight. Causing an intentional delay for retribution is critical and can be damaging not only to the safety of the flight but also to the passengers purpose for conducting business. In essence; the controller is not delaying the crew; but the passengers. Busy radios are the norm and interruptions happen frequently. On a daily basis. We as professionals try very hard to minimize the interruptions and figure out ways to consolidate conversations by communicating most effectively in the fewest amount of words but maximizing understanding. However when controllers do not articulate and get overwhelmed therefore the communication breakdown begins. That is compounded when a controller or pilot becomes angry and allows their anger to be verbalized over the radio. The controller should have recognized the issue at hand and stepped back rather than making an attempt to embarrass someone. They are the ones who can slow things down when they become task saturated. Articulate. Speak clearly. Channel your anger. Leave it at the door when coming to work. I also understand the issues. Some IOE students with limited experience do not have the experience to draw from like someone who has 30 years experience. They will not be eloquent or efficient sometimes. We were all there.There is enough pressure on flight crews without having a controller amplify a situation into an unsafe situation. This controller turned a difficult situation into something much more dangerous. Pressuring and criticizing a flight crew right before takeoff creates a monster of distractions and causes confusion and communication breakdown. I almost turned around and went back to the gate. I asked my students if he was ok and took a moment to regroup before takeoff. I used the situation as a 'teachable moment to explain whathad happened. Mistakes happen; but always maintain a higher level of safety and professionalism. I have emphasized the importance of clarifying clearances and asking again if not certain. Controllers are becoming increasingly less articulate; hurried; and angry; and hostile when asked to repeat. More mistakes happen when pilots are intimidated and afraid to ask for clarification in fear of be publicly humiliated by a controller. This behavior is unsafe and growing among ATC. I feel this should be taken seriously and should be a growing concern. If a violation or accident happens who suffers the consequences? The crew and passengers. So why are we pressured and humiliated by controllers?"