Vital, you must have it. Let's face it, it's a stag do. All boys together means that a stag weekend is often wilder than the usual weekend spent treading the social boards with the bird and her annoying friends. As a consequence you might feel the urge to push the limits a little more than usual, and you want to be safe in the knowledge that should you come unstuck you're well covered.
And while our programmes employ the highest professional codes of practice, our programmes cannot legislate for the unforeseen. That is why we strongly suggest you cover yourselves with adequate insurance. Always check the policy you have / are getting provides an acceptable level of cover for you.
If you're going abroad there are also international considerations, see our international tips. Importantly check if the policy covers you for all potential eventualities from delays, luggage, activities you are likely to do (some policies have exclusions despite their ambiguous advertising) etc. Also pay attention to the payment levels - some are more generous than others (for the same cost) and always check that your international policy covers repatriation.