If you are using your friends laptop and you are not having time to download & install any software or Firefox Add-on to take a full screenshot of a website along with some editing to the same, you can try out Aviary.com which is a Online Image Markup tool called as Talon, helping you to quickly capture images and web pages from your browser and crop, resize or mark them up.
Instead of using different screen capture tools, you can try out the avaity.com online Image Markup Utility which is a Online Application which takes instant screenshot of any webpage URL you specify following which it shows you a list of options which can help you in Editing the Image and adding different Image Effects. Some of the options include Rotate & Flip, Crop & Resize the Screenshot which was generated and instantly apply the effects and view the results on the same window.
The right side menu offers you with options like Undo, Redo, Restore, Colors Selection, Size with Outline & Shadow. You can easily add Arrows by dragging and dropping different pointers from the left side menu. Once you complete editing you can directly save the edited screenshot image to your computer or else save & host online. Overall this is a very much recommended application if you are looking to get some screenshot taken real quickly.