Whilst I cannot confess to have never said any of these myself here are five phrases that you should avoid at all costs when delivering a technical (or indeed any) presentation.

1. I’m sorry you can’t see this at the back. Are you really sorry? I suspect not otherwise you will have made sure everyone could see what you are presenting before showing the slide. Know how big your room is and how big the screen is. As a matter of course never make any font size less than 24 point. Better still avoid words altogether and use pictures or diagrams instead.
2. I’m just going to skip over the next few slides. Why? Either the slides are relevant to what you have to say or they are not. If they are not then they should not be there. There is always a great temptation to include extra slides “just in case”. Don’t! You should include only that which is relevant to what you have to say and discard everything else.
3. Sorry but the colours on this slide don’t show up very well. Using colour in presentations is a great way of getting across information. When used properly colour can be used for emphasis as well as categorising data or information. However, be aware that the way colour can appear on a computer screen and how it can appear on a data projector can be very different. Always use bold colours and, if possible, check out the projector you are going to use before starting your presentation.
4. You probably can’t hear this but I’ll play it anyway. Use of sound and video can be a great way of getting information across and also helps to keep your audiences attention. However if you are using sound make sure you have an effective sound system and don’t, what ever you do, rely on the speakers on your laptop. If you are using sound or video make sure there is adequate kit in the room. As a standby carry a set of portable speakers with you but these will only have limited reach.
5. I’ve only got 30 minutes and we need t get through 75 slides. Or any other large number that will be impossible in the given time. Actually there is no golden rule for how many slides you can present in a given amount of time. If each slide has only a single word or picture then 75 slides in 30 minutes is entirely reasonable. However most times those 75 slides are densely packed with information which is impossible to assimilate in the amount of time allotted. As I’ve said elsewhere don’t pack too much information into your presentation. Instead just focus on the key points and use handouts for detailed stuff.