Collects Groo the Wanderer (1985-1995 Marvel) #37-40. Written by Sergio Aragones and Mark Evanier. Art by Sergio Aragones. Out of print.
From the publisher:
Groo has but one friend in the world -- the loyal, royal pooch known as Rufferto. So what happens when Groo (stupidly, even for him) thinks he's eaten his one friend in the world? This two-part tale from Groo's past, plus two more equally silly tales by Eisner winners Sergio Aragonés and Mark Evanier, comprise the Groo Jamboree!