Kesha marked her 25th birthday party by getting a tattoo.

The 'Tik Tok' hitmaker had such a good time celebrating her big day in March that she persuaded a tattoo artist friend to etch the word 'fun' onto her foot so she wouldn't forget the festivities.

She told Vibe magazine: ''I had a birthday party downtown with a tattoo artist, free booze, and a photo booth. And it was the funnest party ever. Everyone I love was there. I ended the night jumping on a mini-trampoline. So I got the tattoo artist like, 'I need you to commemorate this night with the word fun on my feet.' He was like, 'Really?' And I was like, 'Yeah. Do it.' ''

In September 2011, Kesha - who was named the Humane Society's first-ever Global Ambassador for the animals - secretly made a trip to the Galapagos Islands, Australia, and South Africa to improve her own awareness of animal rights and had an unforgettable experience.

She recalled: ''I went swimming with whales in the middle of nowhere, it was like naked boat ladies swimming with baby whales for a week.

''Then I was rehabilitating baby lions who were like p**sing in my tent, and I was feeding them with a bottle, because their parents orphaned them and they're trying to rehabilitate these other lions that were kept in captivity.''