Flirty Katy Perry gets cheeky with John Mayer as couple enjoy hike with Girls star Allison Williams and boyfriend

Their relationship was doubted by many, but Katy Perry and John Mayer certainly appear to be rather fond of each other.
Showing affection, Katy wasn't shy of placing her hand on the guitarist's derriere as they hiked around Hollywood, California, on Tuesday.
They were joined by Girls star Allison Williams and College Humor co-founder Ricky Van Veen, who have been dating since 2011.
John, 35, even took a second to wrap his arm around his 28-year-old pop star girlfriend, and they continued to hold hands throughout their trek.

PDA: Katy Perry held John Mayer's behin during their hike around Hollywood, California with friends Ricky Van Veen and Allison Williams on Tuesday

Four is fun: The musical couple was joined by their good friends Ricky Van Veen, cofounder of College Humor, and Allison Williams from HBO's Girls

Working up a sweat, Katy had her grey sweater tied around her hips, allowing the breeze to cool her off, wearing a tight white tank and athletic leggings.
And she was definitely prepped for a vigorous workout, sporting a purple sports bra underneath her sleeveless top.
The Born and Raised singer may not own as much fitness gear as his girlfriend though, sporting a printed tee, flannel button-down, and baggy black pants.

Different outfits: John wore a flannel shirt over a printed tee and baggy black pants, as his girlfriend dressed in athletic geaer of a tight white tank and tight black leggings

Love is in the air: Longtime lovers Allison and Ricky have been dating since May 2011, and Katy and John's romance has been blossoming

He wore a bandana around his head to avoid perspiration from falling down his face, and he and Katy both were seen in jet black sunglasses.
Ricky and Allison also dressed down in casual attire for their workout.
The four seemed to be having a ball, smiling and laughing in multiple snapshots from their outdoor adventure, and have frequently been seen out together as they've grown chummy.

Showing affection: John wrapped his arm around Katy's shoulder, and they were spotted holding hands

Ready to sweat: The four dressed in fitness gear and sneakers for their outdoor adventure

Allison was even the Firework singer's date for the 2013 Grammys in February at the Staples Center in Los Angeles.
'She's the hottest date,' Allison said on Anderson Cooper's show.
'She's the best,' she added.

Exercise can be fun: John, Katy, Allison, and Ricky all smiled and laughed as they worked out in Los Angeles

No disputing here: The duo haven't been denying their romance, frequently being spotted embracing their romance in public

And John certainly admires Katy too, telling CBS last month: 'For the first time in my life I don't feel like I'm in a celebrity relationship. I really don't. I'm not in a high profile - I know it's high profile,' Mayer said in the televised interview.
'Doesn't' feel that way to me. And great! I'm glad...For me, it feels like something that's very human.'
His past romances include some of Hollywood's leading ladies, such as Taylor Swift, Jennifer Aniston, Minka Kelly, and Jessica Simpson.