I'm going to be honest - I can be a pretty slack friend when I get my art-related-tunnel-vision happening.
Late to reply to texts / emails / phone calls / facebook messages ... and sometimes I just completely forget all together. A fabulous friend of mine Dave Collinson, sent me a colourful invitation via email because I never answer my phone.
Needless to say, hang outs are happening asap - as a real friend truly would draw me up a personalised invite of my favourite cartoon character. Hah!