Stickers on Thesis paper

With only tikz (don't forget to compile twice if things go wrong):

\documentclass{book}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
  \begin{titlepage}
    \begin{tikzpicture}[remember picture, overlay]
      \node[draw,minimum width=4in,rotate=-45,fill=orange,text=blue,font=\LARGE] at ($(current page.north east) + (-0.9in,-0.9in)$) {Examiner's Copy};
    \end{tikzpicture}
    \centering
    \vspace*{2cm}
    \Large Thesis title
  \end{titlepage}

\end{document}

One possibility using the background package and its firstpage option; you can change the attributes (position, color, opacity, angle of the added text):

\documentclass[titlepage]{article}
\usepackage[firstpage=true]{background}
\usepackage{lipsum}

\backgroundsetup{
scale=2,
angle=0,
opacity=1,
color=red!70!black,
contents={\tikz\node[draw,rounded corners,font=\Huge] {Examiners Copy};},
vshift=2.5cm
}

\title{The Title}
\author{The Author}

\begin{document}
\maketitle

\lipsum[1-40]

\end{document}

A variant:

\documentclass[titlepage]{article}
\usepackage[firstpage=true]{background}
\usepackage{lipsum}

\backgroundsetup{
scale=2,
angle=90,
opacity=1,
color=cyan!70!black,
contents={\tikz\node[draw,rounded corners,font=\sffamily\Huge,fill=orange!10] {Examiners Copy};},
vshift=2.5cm
}

\title{The Title}
\author{The Author}

\begin{document}
\maketitle

\lipsum[1-40]

\end{document}

Although I like the other answers, just FYI, there is package called draftwatermark which allows you to put a background text.

• Use the global option firstpage if you'd like the mark to appear only on the first page.
• With \SetWatermarkColor[rgb]{1,1,0} you could change the colour. Otherwise, in the grey scale, the option \SetWatermarkLightness{0.7} change the grey value.
• Change the scale of the mark with \SetWatermarkScale{3}
• And the text with \SetWatermarkText{Examiners Copy}

All together:

\documentclass{article}
\usepackage{lipsum}

\usepackage[firstpage]{draftwatermark}
% Use the following to make modification
\SetWatermarkColor[rgb]{1,1,0}
\SetWatermarkAngle{45}
\SetWatermarkScale{3}
\SetWatermarkText{Examiners Copy}

\title{Lorem ipsum}
\author{O. Castillo-Felisola}

\begin{document}
\maketitle

\lipsum[1-5]

\end{document}

This code produces:

Cheers!